This is why I like Obsidian (or some other linked-documents wiki type of system), because it makes linking things easy, so you can take multiple routes to find a thing. I have a health note and a finances note. Which one does health insurance go under? I pick whichever one seems to make the most sense at the time. Then, in the future, if I'm looking for health insurance and look in the wrong place first, I can easily make a link there to the "health insurance" note/section. Now, I will find health insurance whether I look under health or finances.

The "Obsidian way" that many people recommend is notes that are as small as possible to maximize this kind of effect, but that's not how I like to do it. I prefer bigger notes with lots of headings (that can be nested up to 6 levels), and lots of links within a note and between notes to specific headings. I find this to be a nice blend of hierarchical navigation and link navigation.

Non-text files (like receipts or pictures) get linked from the relevant note or section, and many types of media can be viewed inline in the WYSIWYG editor.