If you are storing any significant amount of BTC, you really need to be using multi-sig. Even if you hold all the parts, it's still going to provide more security, at the cost of convenience, than a single-sig. Multi-sig can also help prepare you against things like natural disaster, your own death (for passing on to heirs), etc.

You can't reasonably store a backup of you single-sig anywhere with any party without completely trusting that party. You can reasonably store a part of a multi-sig with another party without needing to trust them completely or really even at all.

Likewise, if you're the "bury your Bitcoin seed in the woods" type, if somebody finds your stash? They found your bitcoin. If they found 1/3rd of your stash? Good luck finding the rest.