What's your worldbuilding quirk?

All right, all of us here are worldbuilders, but we are not all the same. So what's that one part of your worldbuilding that may seem strange to others, I'll go first.

I actually have two. #1. Irl stuff. I have a ton of random stuff laying around. So sometimes I'll see a shiny rock or cool Lego figure I made 6 years ago and say, "I'mma put you in there." Ant then it's some magical item or famous ancient hero or something.

and #2. In universe books.I do not know why, but I really like making books from my story IRL. This is often a way for me to write down my magic system or history in a way I find cooler or more fun. For example, I was thinking about how dark magic works in my world, so I made a book of dark magic. I was working on it for a little while knowing it was canon, but not who made it or when.

So, those are mine, but what are your quirks?