I started my own TIL collection inspired by Josh and it's been fantastic - I'm up to 102 now: https://til.simonwillison.net/

The thing I love about these compared to regular blogging is that they reduce the barrier to writing something up to almost nothing. Did I learn something? If yes, I can write it up as a TIL - no pressure at all for it to be anything novel or interesting to other people.

I refer back to mine a LOT. The principal audience for them is future me - if anyone else finds them useful too that's just a bonus.