"Completing a project" is not the same thing as ending the project management process. Simply finishing doesn't ensure that the organization benefits from the project's outcome.
HGT Define the scope of the review beforehand. Given the number of people often involved in a project, it's easy to hurt someone's feelings when reviewing the project's success. We clarify our objectives for the review, and make our intentions clear, this ensures that people share their experiences openly and honestly.
We gather together the key project documents. This will help us assess the project planning process, as well as the actual benefits achieved through the project.
Generally HGT use outside consultants in the review process in order to get an objective, unclouded view of the project.
HGT then report our findings, and publicize the results.