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The Intrinsic Link Between Cost and Schedule

My maternal grandfather once told me that his grandfathers each had diametrically opposed mottos. His maternal grandfather’s motto was “Haste makes waste,” while that of his paternal grandfather was “Time is wasting.” My grandafather said he found these two views to be confusing. I asked him what his motto was, to which he replied, “More fool, more fun.” I have found a way to reconcile these two seemingly contradictory statements. Both are true depending on the circumstances.

In my work in estimating cost, schedule, and their risks, I have found that both are true depending on the circumstance. There is an intrinsic link between cost and schedule. For a given scope, there is an optimal schedule. Anything shorter than this optimum will lead to higher cost. To achieve a tight deadline, some work planned to be sequential will have to be done in parallel instead. Also, workers may have to work overtime and in some cases, multiple shifts will be required. This is the “haste makes waste” effect. On the other hand, longer than optimal schedules also require more cost. For each project, there is a large set of fixed labor that charges to the project. If this standing army works for a longer period, cost is higher. This is illustrated in the graph below.

Note that the effect is not symmetric. Norm Augustine, former CEO of Lockheed Martin, once wrote that stretching a schedule is the second costliest action a project can take. The costliest possible action is to compress the schedule. This kind of schedule compression happens frequently in space missions to other planets. NASA sends missions to Mars on a regular basis. There is an optimum time to launch, when the Earth and Mars are closer together. If this window is missed, there will be a two-year delay until Earth and Mars are closer together again.

There is some flexibility in setting up a schedule early in a project. However, once plans are in place, any change will increase cost. This is similar to a position in chess known as zugzwang, which refers to a position in which any move will weaken a player’s position. Chess players have to make a move each turn, but projects can in many cases avoid making changes. However, this requires discipline. It sounds simple, but that does not mean it is easy. Projects are notorious for changing requirements during the development. This inevitably leads to schedule delays and cost growth.

For more information on project cost and schedule growth, you can read Chapter 1 of my forthcoming book Solving for Project Risk Management: Understanding The Critical Role of Uncertainty in Project Management here.

The book will be released on November 3rd, but you can pre-order now from Amazon and Barnes and Noble, in both hardcover and e-book formats.