I would assume that this is not a factor with RAID-1, where all system, metadata, and data is duplicated. I could see this as being very important for the higher RAID levels.
We have since stopped deploying any sort of btrfs RAID (even RAID-1), and have gone back to using Linux MD.
https://ohthehugemanatee.org/blog/2019/02/11/btrfs-out-of-sp...
If I could mount the failed btrfs filesystem read-write for an appreciable length of time, I could try the balance operation.
I'll need to set up a cron job on the other systems to run balance on a regular basis alongside scrub (obviously not at the exact same time).