Im kind of like you. My answer to this is what I call "breadcrumbs". I leave them everywhere, and rely on fast searching tools.

In onenote, I make sure things have unique keywords I can search for.

I use "Everything" or "Fsearch" to find files on my harddrive. It even indexes my onedrive.

Emails? Git gud with searching boolean queries. From:fred AND body:football

I've similarly tried various organization methods and I cant seem to maintain them. Focusing on easy search has been my way forward.