Project management plan (PMP) is a living document. The timeframe should not cast in stone. The schedule must change accordingly due to various factors as capture in PMP such as risk, assumption, constrain etc. The project manager (HOPT) as team leader must be sensitive with the changes.
In JKR, PMP is not used widely as planning and managing tools. Then, the blaming games occured between team members. High leadership quality is in demand.