In addition to understanding the decisions made in the past, looking over the lessons learned provides invaluable insight that can be used to streamline a projects progression. The obvious reason as some mentioned is learning and avoiding past mistakes made. In addition, taking certain courses of action based on previous decisions in the past to ensure a timely completion is another benefit of a lessons learned. The lessons I believe are particularly worth recording include: the time frames for deliverables from 3rd party vendors, unexpected decisions/justifications from upper management in any magnitude, and of course all estimates for tests, parts, and materials. These few items are some of the most critical variables I’ve noticed that redirect the path a project takes so having as much insight as possible on them would certainly prevent delays and other situations down the line.