When should we use resource leveling rather than resource smoothing?

When a project falls behind, there are two classic approaches. They address different problems, and choosing the wrong one is a common reason why the situation gets worse.

Resource adjustment — when the deadline can be moved

Here, you adjust staffing and allow the timeline to extend. This is suitable when you have limited or shared resources but flexibility regarding when the project needs to be completed. The advantage is that people are not overburdened; the disadvantage is that the completion date is pushed back.

Resource smoothing — when the deadline is fixed

Here, you optimize the use of the resources that are actually available within a fixed deadline. This is the right approach when the end date has been agreed with the customer and cannot be changed. The trade-off is that it places greater demands on how accurately the resources are recorded—if the capacity in the system is incorrect, the leveling will also be incorrect.

The question you should ask first

What is actually fixed—the date or the people? Surprisingly often, it turns out that the date is less set in stone than assumed, or that capacity is available in another department. Either way, both techniques require the work schedule to be up to date. If it is not, you are optimizing based on incorrect information.