The Project Management Body of Knowledge (PMBOK) refers to the process as lessons learned.
[1] Project post-mortems are intended to inform process improvements which mitigate future risks and to promote iterative best practices.
Post-mortems are often considered a key component of, and ongoing precursor to, effective risk management.
Successful analysis of project estimate variance is dependent on accurate time tracking.
The greater the granularity with which time is tracked, the more detailed an analysis can be performed during the project post-mortem.