Apart from forgetting the encryption password, here's another scenario. First: when you say 3 backups, does that include the wallet you're using? I assume so. So by the time your system fails and you realize you need your backup, you'll only have 2 backups left. You're nervous, not very careful, and before you know it, you have only 1 backup left. Or you messed up one of your backups while you created it.
Do you at least check if you can restore from your backups once in a while?
To be honest, I'm doing it but not with my savings' stash.
So, the way I do it is very similar to what I'd do if my whole savings existed in a Core
wallet.dat file. I don't do it with my stash because I'm too idle when I need to make changes like this and, at the same time, I'm too used to using the other system that I use.
But, with Core, I'm doing the following:
1. I have the
wallet.dat file on an airgapped laptop, loaded in Core, signing transactions.
2. I also have 2 backups in USBs (which is my pain-point). I think USBs are the worst option.
3. Every 6 months, I have set a notification and I load the backups to my laptop to see if the loading happens perfectly. I also create a new backups to my USBs.
4. Every 2 years, I rotate my backups to new USBs. (this step has only happened once, but next summer I'll need to repeat it).