While I personally have not worked on a project team where a lessons learned document was utilized, If I were a project manager I would make it a practice to always start a project off by having each team member briefly read through the previous document. This way if the members encounter any difficulties that can be solved with advice from the lessons learned document, they will recall reading something relevant and can go back to the document and read it more in depth. 

It's always important to look back at any lessons learned document because as you said, knowledge transfer is key. I've seen too many times where a new hire comes onboard and really lacks a lot of critical knowledge that can ease the transition due to no lessons learned documents being available. I feel that if I was a project manager, I would always require a lessons learned document to be made and plus if there are such documents available, to look back at the resources to gain more knowledge. For example, in my time as a validation engineer I would make it a habit to always look back at previous validations to analyze some of the shortcomings in the validation and how to best approach future validation projects.

While never have had experience in a lessons learned document, i think this should be applied before every meeting of a big event, or every time the team meets to discuss updates of the project. Having the lessons learned document shows the failures and successes of the entirety and its something each team member should know. I think at meetings it should be addressed for everyone to read the lessons learned, and possibly go around putting feedback. This would allow for people to openly speak on why something was successful or unsuccessful, as well as allow for input on how to improve! 

Lessoned learned documents are incredibly useful for the success and continuation of a project. I remember when I was a part of a senior design capstone project I utilized a similar document to continue a project left by the senior class before me. The document explained all of the success, difficulties, and downfalls of the project which I ended up using religiously for the entire duration of the project. After the project I also wrote a similar lessons learned document for the next group, ensureing I captured the entire ups and downs from the project. From my own experience I say for every project, the team should use the lessons learned document before starting the project so they can accurately plan out the project. Once they plan out what needs to be done then they can use this lessons learned document as a reference as needed.