Under what circumstances might you wish to crash a project?

Crashing may be desirable if initial time estimates are inaccurate, the project falls behind schedule or the project completion date is moved up.  In these cases, the project cannot be completed on time given the original schedule.  Crashing would expedite the project/activities to meet new completion dates.  Another scenario occurs when late fees or penalties may be incurred.  It may be more cost effect to crash activities than to pay the additional fees.