Explanation
The lessons learned document is a document that captures and documents the successes, opportunities for improvement, failures, and recommendations for improving the performance of future projects or project phases. The lessons learned document is updated throughout the project lifecycle, not just at a specific phase.
Updating the lessons learned document throughout the project lifecycle helps to ensure that the valuable knowledge and experience gained from the project are recorded, shared, and applied in a timely and effective manner. It also helps to avoid repeating the same mistakes or missing the same opportunities in the current or future projects1. The lessons learned document is updated at the end of each project phase or iteration, or whenever a significant event or change occurs in the project. The lessons learned document is also reviewed and finalized at the end of the project, as part of the project closure process23. References:
CBAP Handbook
Business Analysis Body of Knowledge (BABOK Guide) - Version 3, section 7.6 Manage Project Closure Lessons Learned - iiba.org