Ray Stratton's news letter just arrived. There he speaks to the "44 Day Rule," for the duration of work activities. Some places use that for the duration of a Work Package. Other places use that as the duration of a work activity contained in the Work Package.
Here's another idea.
You need to answer the question - How long are you willing to wait before you find out you are late?
The answer to this question, then drives two things:
- The duration you will measure physical percent complete, to assess your progress to date, and the estimate to complete.
- This duration needs to be son enough to take corrective action to not be late.
With the answers to these two questions, the duration of a work activity should now be self evident. As well as the point in time needed to take corrective action. This corretive must have enough time to have the lateness be fixed. So some arbitrary durations cannot be used. You need to know how the work is being performed.
But a simple (and simple minded) rule assumes the work is being performed linearly. So yuo can answer the question by saying, what is the capacity for work that must be applied to fix the activity when it gets behond schedule?
By the way, when this corrective action is applied, it will cost more money, unless you change the scope or improve the effectiveness of the work to cover the extra work needed to correct the problem.
This is why short duration activties are best. The Agile folks know this, maybe not for the same reason. But short duration tasks - the 44 day rule - force the assessment of work so corrective actions can take place.