Buffering the Schedule
The other problem that we addressed was what to do if the schedule is earlier than the promise date (12) of the project to the stakeholders. This is a much more pleasant problem than trying to shorten the schedule. It is a very important problem to solve, however. This must be done after allowing for reserve schedule time, normal fluctuations in the activity durations, and resource limitations on the schedule (figure 2-7). If after all of this the schedule time is less than the promise date, buffering may be applied.
Figure 2-7. Schedule without contingency.
A project schedule should not be adjusted by lengthening the duration ...