Some of them I remember and refer back to often. Others I completely forget even exist.
I added "related TILs" to my site a while ago - here's a TIL about how I built that: https://til.simonwillison.net/sqlite/related-content - and as a result occasionally I'll post a new TIL and the related ones will remind me of an older one.
Occasionally I'll completely forget the subject of the TIL itself! I was delighted to randomly stumble on this one here https://til.simonwillison.net/html/datalist the other day (after clicking my "html" tag from another TIL) which reminded me of the HTML datalist element, which I had forgotten existed.