I'm going to be facilitating a second lessons learned session later today. As part of the project closing processes, all project managers should collect and document lessons learned.  But, as many will attest, you need to be able to implement approved process improvement activities or you will just continue to revisit history at the end of each cycle or project.

Do you learn from your mistakes?  You should be able to at least be aware of them if you document them at the end of each cycle or project. Revisit them at the beginning of the next project or cycle.

Corrective Action:  Document your direction for executing future project work. Bring expected performance of the project work in line with the project management plan.

Preventive Action:  Document your direction to reduce the probability of negative outcomes associated with project risks.

Defect Repair:  Document a defect in a project component with the recommendation to either repair it or completely replace the component.