Personally I use a single folder named "kb" (short for knowledgebase). This folder contains every single file I've considered worthy of saving. I keep backups and sync between all devices.

The secret is in the naming conventions. I've written about mine extensively here on HN [1], so I won't go into too much detail here, but for your receipt example I'd do `fin.receipt.[date].eye-doctor-visit.png`.

Family members files should be in those people's home folders. Mixing people on one account is just asking for trouble in my opinion. If they're an enumerable number of important documents, consider a central family folder which gets backed up frequently, with a subfolder for each person and one for shared family stuff.

- [1]: https://news.ycombinator.com/item?id=41370673#41373817