1/ My thesis that by externalizing our thoughts by writing them out, we:

~Understand if we understand or not (writing is a forcing mechanism);
~Quickly see holes or problems in our ideas that we wouldn't grasp if they just remained in our thoughts;

2/

~Externalize our thinking in time such that our minds can't helpfully "update" our memories to make them consistent with what we know and think now (hindsight bias);
~Help us understand WHY we were thinking things at the time and remind us that our "memories" are unreliable

3/ narrators. There's nothing quite as shocking as truly thinking you thought something during some event and then being called a liar in your own handwriting.

This is vital for correcting our errors and updating our mental models. I simply can't think of any other easy activity

4/ that has a higher ROI than this in terms of upgrading and learning from your mistakes. I'm pretty sure if I hadn't been doing this all of my adult life, it wouldn't have been nearly as easy to write this: https://jimoshaughnessy.tumblr.com/post/175118354574/mistakes-were-made-and-yes-by-me

5/ And here's a longer thread on why I think documenting your thinking is something that gives you a huge advantage over those who don't: https://twitter.com/jposhaughnessy/status/1218578824197218309