Are the resources scheduled smoothly?
Projects may be either schedule-driven or resource-driven. If they are schedule-driven, you have a fixed deadline, and you must allocate sufficient resources to do the work within the time frame. If the project is resource limited, the schedule must stretch to accommodate this constraint. Of course, the scope may be changed to work within either constraint. Remember the triangle.

When the schedule is created and resources are allocated to the control tasks, you may find that key people are either over-allocated or under-allocated. They may be scheduled to work on several tasks all at the same time, or there may be gaps in the schedule when they appear to be working on nothing. This is when project managers try to move tasks around within the available slack to “level resources.” This is a productive exercise, and it can help to smooth the work load of key resources. Resource plans work best when resources are scheduled to enter and exit the project in a smooth fashion. Why?

The resulting histogram is “ramp-up, ramp-out.” The project starts slowly as people are added, increases to maximum activity, then people are released back into their functional departments as their work is completed.