Do you use redundancy in your backup solution(s)?

I mean drive redundancy, I.e raid/mirrors in a single backup solution, like for a separate nas. If I backup all my stuff onto a single striped drive, and it fails, I still have my working storage that I can backup to a new working drive no? Only situation where I see it beneficial is for ransomware that waits a few weeks until activating, at which point the backups without it would be critical. But despite its severity I don't think it's likely enough to happen to be to justify spending (at least) 50% extra on space I can't use. Besides if I follow the 3-2-1 rule i'll still have a copy somewhere else if one of the backups fails.