Do your schedule tasks have excessively high or long durations? The Defense Contract Management Agency (DCMA) says activities longer than 44-days (approximately 2-months) are not ideal, and should be limited.
The quality of schedules is certified by the DCMA 14-point assessment. Schedules that meet or exceed the assessment have a significantly greater opportunity for success. The high duration task assessment considers the number of long duration tasks, which it defines as tasks having a duration longer than 44-days. Accordingly, no more than 5% of tasks may have a duration greater than 44 or the schedule fails this assessment, and requires further review; with the exception of long lead procurement activities or level-of-effort tasks.
This article discusses the DCMA high duration tasks assessment as a measure of the quality of a schedule.
High or long duration tasks have the following disadvantages:
- They make discrete progress measurement more difficult.
- They increase the possibility of required changes to in-process work.
- They may distort the critical path.
- They are more susceptible to the negative lag relationship modifier.
The DCMA high duration task assessment places limits on the maximum allowable task duration. But what about long duration projects? Should the task durations of lengthy projects be limited to 44-days? To uses an extreme example, a former student that works for NASA estimated that a mission to mars; including concept, prototypes, final design, production, launch, and travel to mars, would have a duration of, perhaps, 20 years. If this is your situation then what would you make the limit or maximum duration of a single task?
Discrete Measurement Issues
The answer to this question depends on the level of work package decomposition required to make activities discrete enough to track and manage. Again, the DCMA high duration task assessment says that no more than 5% of tasks should have a duration greater than 44 working days. So 44-days is the cutoff.
Why 44-days you may ask? Well, tasks greater than this are more difficult to track and manage. Also, schedules are commonly tracked or progressed on a monthly basis. One would expect tasks to either start or finish during this normal status cycle. So excessive duration tasks (in a seemingly endless in-progress state) make it harder to get visibility into the project schedule status and progress. Short and long duration projects, and even really long duration projects, therefore all have the same acceptable task duration requirement. Yes, long duration tasks make discrete measurement more difficult.
When it is not possible to foresee all future activities and discrete work packages in a project implement rolling wave planning should be used. Project planning in rolling wave is done in stages or “waves” where activities in the near term are planned in detail and activities farther out in time are left for future planning. Rolling wave near term activities are discretely defined but farther out activities are more generally defined and more pliable. These farther out activities should, perhaps, include the labeling ‘planning package’ in their title name. So ‘planning packages’ represent far-term effort where definition of discrete work packages is presently unknown, but the schedule is to capture all scope. This is common practice in earned value project management.
In-Process Work Changes
Long duration tasks also increase the possibility of required task changes to in-process work. In this situation the task is so long that part way through implementation it is discovered that an adjusted definition of the work is required. Shorter tasks provide more clarity and accuracy of the actual work to perform. Shorter tasks are more measureable.
Distorts Critical Path
High duration tasks may also distort the critical path. The thought is that a long duration discretely defined task is not accurate, and, therefore the associated task duration estimate is also incorrect. Distortion of the critical path either to the long side or short side is the likely result. You would be better served, again, by implementing rolling wave planning where short near term tasks are discretely defined and far off efforts are described in high level ‘planning packages’.
Negative Lag Modifier
Long duration tasks are also more susceptible to the negative lag relationship modifier, which is another DCMA lead assessment described at the following blog The DCMA 14-Point Assessment and Negative Lag (Lead).
Note that leads are discouraged and even precluded in the 14-point assessment. You do not want leads in your schedule. But your long duration task may make strict adherence to the connecting predecessor/successor relationship more cumbersome. Where the joining relationship is finish to start (FS), in particular, you may be tempted to commence the successor activity before the full completion of the predecessor activity. This is the FS negative lag scenario where strict adherence to the FS relationship is not maintained.
One problem with negative lag is its predictive nature; you are deciding to commence a successor activity early based on the predicted future completion of the predecessor task. This predictive nature of negative lags makes them problematic. Keeping tasks within the acceptable 44-day duration makes the prospect of negative lag insertions less likely. So negative lags are forbidden by the 14-point assessment and long duration tasks that make them more tempting are discouraged.
Long duration tasks are allowed, however, according to DCMA no more than 5% of tasks may be high duration. Long duration tasks require careful inspection. Discrete measurement of long duration tasks is more difficult and less accurate. Long duration tasks may require in-process scope or activity definition changes.
Critical path distortion is also a real possibility. And the temptation to insert negative lags is a real problem; negative lags are forbidden by the 14-point assessment. Implement rolling wave planning to discretely define near term tasks and broadly estimate planning packages of farther out more malleable work efforts. Yes, the high duration assessment supports avoiding schedule pitfalls made more likely by the prevalent use of long duration tasks.
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