I go against recommended practice and have different vaults for different things in my life. The academic note vault is separate from the personal vault is separate from the creative projects vault. I have also committed sacrilege by not having many notes linked to each other. I’m trying to migrate a lot of notes from Google Docs and Notion over into Obsidian, so all of the vaults are pretty messy.
I love the LaTeX integration. Lots of math formulas in the academic note vault. I use the callout feature everywhere. I also nest callouts in callouts. I’m frankly treating them as equivalent to toggles in Notion.
I most often go to the personal vault where I have a list of things I’ve 1) seen online before, 2) spent at least an hour trying to refind that thing later and 3) will probably want to find again. This way I don’t lose time trying to find it again. It’s really helpful for me. I also have a list of food brands and how much I liked them, so I can remember which brand of turkey was bad and which was tolerable and which I’d definitely buy again.
I have a work environment, which has a symlink to my private notes. Then I use it for some other stuff too with separate, tinier vaults, but I found that unless it's accessible in my primary vault, it will be ignored and forgotten.
But it does get annoying when is search I find both Linux notes, interview notes, and D&D notes.