How Much Is Too Much?

  Estimating  

In Excessive Schedule Pressure, I describe why project managers should never excessively try to compress a project schedule. What I failed to do, however, is define the term “excessive.” As a project manager, how can you determine if your schedule is aggressive yet realistic, and at what point does it become overly optimistic? How much is too much?

The Efficient Project Schedule

 The law of diminishing return explains that every project has a point beyond which each additional resource will be less productive than the previous one. That point is the Efficient Project Schedule (EPS), sometimes referred to as the “nominal” schedule.

The EPS is an aggressive, realistic project schedule that is effective without wasting resources. It should be used when the cost of a project is relatively more important than time to market.

The following mathematical expression allows you to estimate the duration of the EPS:

D = K * E^(1/3), where: 

• D is the duration of the project
• K is a constant (usually 3, but can range between 2 and 4)
• E is the estimated effort for the entire project, in person-months

Imagine a project that was estimated to take 100 person-months to complete. According to the EPS formula, the time required to complete the project is approximately 14 months [D=3*100^(1/3)]. Given that the overall effort is …

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