I keep a running Google doc consisting of Things I've Learned, and append to it whenever something interesting or insight-generating happens in life or work (even if trivial, eg "it's really important that we review Product PRDs the same way we'd code review a pull request, I should write that down").

I review my now-very-long doc every few quarters and it's an easy way to reinforce core concepts that I'll want to share later via writing, mentoring, advising, etc. This question seems more technically focused, but this has been a great way to learn and internalize experiences. Granted, it's probably a better system for gaining "wisdom" as opposed to hard technical knowledge.