The essence of a good schedule
Plans are nothing; planning is everything - Dwight D. Eisenhower
A good schedule describes the sequence of activities which can be followed to execute a plan. This sequence lays out the work packages described by the plan in the proper order so their outcomes can be achieved, and so the consumption of resources and production of products is efficient. The duration of these activities is determined by the level of available resources, and by the rate at which results can be produced when these resources are applied to them.
In small bites, a schedule depicts activities and their dependencies for an endeavor. But when endeavors are complicated and involve many pieces, it is likely that a particular kind of schedule is used - an integrated master schedule which links the information in an accompanying integrated master plan for an endeavor, instantiates that information through the network logic established by lower-level schedules, and optimizes the allocation of available resources and time. Through this means, the integrated schedule establishes dates when key events are expected to occur, and weaves together the work packages necessary to achieve the corresponding accomplishments.
An integrated master schedule is thus a time-based depiction of the information contained within the integrated master plan, with substantiation of this depiction through lower-level schedules which implement that plan, and depict how the work will be performed. The use of the adjectives ‘integrated’ and ‘master’ in this context have the same meaning as they do in the corresponding integrated master plan.
A good schedule requires elaboration of details and concurrent sizing of the work to be done. Each require collection of facts and data about that work, so that appropriate modeling of this work can be performed. The organization which charters the development of such an integrated master schedule must commit to proactively use the resulting information (instead of optimism, opinions, or ill-defined targets); it must also then manage the lower-level schedules, or the resulting top-level schedule will be meaningless. While many think schedules are a joke, that attitude is a self-fulfilling prophecy.
In reality, schedules are just a tool, and should not be confused with the challenges that may actually be encountered while performing the work. The process of developing a schedule can be as important as the schedule which results from that process, since this journey itself often serves as a catalyst for discussions which may not otherwise have happened. In the absence of sufficient attention to planning and scheduling, precious time and resources may be wasted on relatively unimportant activities as the work unfolds, and many options for mitigating risk will be missed until it is too late to exploit them.
Work packages owners (i.e. those primarily responsible for producing the results expected from the work packages) must work together to translate the activities, events, and accomplishments described in the integrated master plan into specific dates by:
aligning with the equivalent planning & schedule models of the higher and lower level schedules for an effort
connecting with upstream, concurrent, and downstream performing organizations
working through the needs of customers, including those of downstream performing organizations
negotiating interactions with other work packages owners
taking account of estimates for the demand and the availability of critical resources
An integrated master schedule should be presented as a structured hierarchy which make the key activities, milestones, and interdependencies between the constituent work packages visible. An integrated master schedule models the logic of these interactions (i.e., their predecessors, successors, and associated lag or float time) in order to depict how accomplishments will be achieved with the passage of time, and through the expenditure of resources. This hierarchy should also align with realistic start dates and needed end dates to lower level planning efforts. When seen from this perspective, an integrated master schedule is really a network of commitments. The combination of these commitments for individual work packages, their predecessor and successor relationships, and their triggering conditions, are what enable a critical path analysis to be performed, and resources to be optimized across a portfolio.
The integrated master schedule should be a living document that is regularly updated to reflect the progress of the program or project. The information in the integrated schedule network should be logically consistent, and the collection of resources required should sum to the budget agreed to for the endeavor. This collection should also:
Maintain consistency with the integrated master plan
Illustrate the interrelationships among events, accomplishments, criteria, and tasks
Maintain consistency with the work package definitions
Indicate the start and completion dates and duration for each event, accomplishment, criterion and task;
Provide the ability to sort schedules multiple ways (e.g., by event, by work package owner, by type of funding required,?etc.
Provide for critical path analysis;
Provide the means to perform ?what if? schedule exercises
Provide for updates on a regular basis, and record completed actions, schedule slips, and rescheduled actions from the previous schedule for reference
This network should include all the elements necessary for achieving the accomplishments. For example, if the project in question is an engineering development project, it should include requirements elaboration and clarification, design and development, verification and validation, production or modification, and delivery of the total system. The work required for these activities should be described within a context which is meaningful to running the business. This network should provide the basis for critical path analysis, establish a framework for identification and assessment of disconnects, and allow alternative scenarios to be explored. The progressively increasing level of detail in these schedules across the schedule network or hierarchy should include:
A summary schedule, typically depicted in a single view, which highlights the period of performance, key milestones and/or deliveries, and other significant events
Intermediate schedules, which represent work package or project activities, milestones and phases at a level of detail which is below, but vertically traceable to, the summary schedule. Intermediate schedules are used within performing organizations to manage their commitments and communicate their progress
Detailed schedules at the level that the work is being done within the formal network, and are the sources of the data that drives the summary and intermediate schedules. Detailed schedules elaborate authorized work into a logical sequence of time-phased tasks and interrelationships, and provide meaningful indicators of work being accomplished at levels below the formal reporting threshold. For example, such detailed schedules may not track individual change requests, but instead would the activities which must be implmemented to deliver a collection of these work requests over time.
As this elaboration is performed, the resources required to accomplish these work packages can begin to be rolled up and examined in aggregate. It is at this point that the total demand on available resources will become apparent. Generally, adding resources to meet the demand should be a last resort, because most resources are not interchangeable, and growing the team will increase the costs of coordination, communications, and decision-making. A preferred alternative is for the scheduling process to rearrange the order in which these work packages will be executed; however, this process should not try to change the underlying structure or approach to doing the work, unless the associated integrated plans are themselves updated.
Negotiations typically begin in earnest when such resource or time conflicts become apparent. A strategy will need to be developed so that tradeoffs among priorities and alternatives can be performed. Ideally, these tradeoffs should avoid erosion of contingency buffers which are necessary to absorb the inevitable risks that will arise. To the extent possible, this reconciliation should be performed so as to preserve the ability to accomplish events in the higher-level schedules, though often, the results of these discussions may also rippleinto requested changes to the integrated master plan itself.
For complex projects or portfolios of related projects, use of a work breakdown structure (WBS) will be helpful to organize the work packages and activities associated with an entire portfolio of projects associated with some endeavor. This work breakdown structure provides a framework and context for collecting costs, reporting progress, and providing oversight by different levels of management, and across different levels of this schedule hierarchy, with respect to the actual status of the individual elements contained in this structure. The work breakdown structure may also organize this work across major phases, such as pre-acquisition, acquisition, and sustainment, to emphasize the necessary lifecycle implications of an endeavor over some planning horizon.
Events and deadlines are typically represented on a schedule using a milestone notation. All such notational conventions should be established up front, for consistency across the schedule network. These standards should also describe how the planned start and finish dates of activities, and the relationships between these activities, should be depicted, as well as provide a means of communicating and managing schedule baselines. As work is performed, a similar convention should also be adopted to depict progress which has been achieved. This convention should also draw attention to the impact of prior delays on work in progress, as well as work planned in the future.
The basis of estimates for the durations of activities should be traceable to realistic projections of effort for the size and complexity of all products which must be produced. Whenever possible, the analysis behind these projections should be calibrated with data from prior experience. While an integrated master schedule should be an event-driven depiction which has been derived from the projected durations of the underlying activities, there may be specific constraints on when individual events must be accomplished by (i.e. no later than dates). A periodic schedule analysis should be performed to evaluate the realism of any sequence of activities relative to such constraints, as progress unfolds.
The path originally envisioned by the integrated master schedule may turn out to be unrealistic, once execution begins; those who are responsible for managing to changes to the schedule should keep in mind that the map is not the terrain. High-risk, concurrent activities may be attempted, and aggressive estimates may be prescribed to meet emerging conditions. For an integrated master schedule to be effective, it should not override what can realistically be done; instead, schedule risks should be identified, and timely mitigation efforts should be put in place to attempt to shorten time flows which don’t fit into overly ambitious targets. The integrated master schedule should then explicitly include these known risk reduction activities which are expected to mitigate these risks, and include the associated resources required for performing this mitigation.
Scheduling tools and the specialists who use them can steer projects into trouble if these tools are used to spread resources in artificial ways, such as by capping resource consumption at some level or forcing the spread of resources to match available funding. Handoffs between individuals are rarely clean unless there is a robust process in place which communicates the protocols of these exchanges. For example, while gantt charts can be useful representations, the activities which they depict can be misleading unless they are integrated, and their start and end dates match the criteria established in an integrated master plan. The resulting allocation may not actually be practical or realistic, but those reading the schedule will not be able to tell the difference. People can’t multitask from one task to another without reorientation and loss of efficiency. Another pattern often observed is for teams to locally authorize shifts to events for their own convenience, without requiring corresponding reviews and authorization of the direct and indirect impacts on other work packages.
There are many practical scheduling guides available that offer good advice about how to satisfy the above provisions. One of the better ones is the Planning and scheduling excellence guide, which is available from the NDIA. This guide provides eight over-arching tenets for building, maintaining, and using schedules using what is described as ‘Generally Accepted Scheduling Principles (GASP)’.