A while ago, I listened to an investor share that he keeps a log of all his lessons learned from each investment. (This is different than the investment memo that he writes when he’s evaluating whether he should make the investment.) After the investment is made, he keeps a log of lessons and observations. He started the log to try to minimize making errors more than once. Identifying the lessons, writing them down, and reviewing the log periodically was helpful to his investment process.
I’ve started a similar log, albeit a less formal one. I’ve been keeping a running list in the Notes app on my iPhone and laptop. I recently reviewed the log while considering a new investment and altered my approach to making that investment because of a lesson learned.
I’m a fan of logging my lessons learned. I hope to keep the habit up and compile a single list of lessons learned over many years that I can eventually share.