I am only about 100hrs in, been getting in and out of it over the past months. I admire your dedication though! Do you think you're done with TotK forever, or do you intend to replay it?
How do you track old maps? I think I have them all just based on my thorough exploration of the sky islands, but would be cool to know for sure.
Old maps show up in your special items inventory; whether the chest they point to has been opened yet or not. To know that I had them all, I just looked up how many total there were. Same with Yiga Schematics and Schema Stones.
I don't see myself replaying the game much; but I did just start a new playthrough for a very specific purpose... I want to get all compendium pictures manually. I plan to do the minimal amount necessary to make that as fast as possible. So I'll do some shrines just because the extra stamina and hearts will help with faster progression in general, but no idea how many. So far in just a couple hours, I've gotten off the great sky island, gotten the camera, and taken somewhere around 70 pictures. It's a fun challenge at the start because new stuff to add to the compendium is just everywhere. It will get more tedious when it comes to hunting down the remaining ones; especially pristine weapons. Doing this will require beating the game, to get the Ganondorf pictures.
One of the reasons I'm doing this is because there's a quest, "filling out the compendium", which is started when you first get the ability to purchase new compendium entries, and completed when you purchase your first entry. I want to see/know how it gets completed if you never purchase an entry. At the least there must be some different dialogue or something. No one on Reddit seemed to know the answer.