I do a thing before any sizeable package upgrade on my laptop: take a read-only btrfs snapshot of the root subvolume. It costs nothing, it's instant, and most of the time it's a snapshot I delete next week having never looked at it. This Saturday was the other kind of week.
An upgrade pulled in a new kernel and a graphics driver that did not like each other, and the machine booted to a black screen and a cursor that wasn't interested in talking. Normally this is where the evening disappears: boot a USB stick, chroot in, work out which package to pin, swear gently at nobody. Instead I had a snapshot from twenty minutes earlier.
btrfs subvolume snapshot -r / /.snapshots/2017-02-10-pre-upgrade
That -r was the line I'd run before touching anything. To recover, I booted the live USB, mounted the btrfs pool, swapped the broken root subvolume out and the snapshot in (set it writable, point the default subvolume at it, fix /etc/fstab if you've been clever with subvol IDs), and rebooted. Five minutes. The machine came up exactly as it had been before the upgrade, because that's literally what the snapshot was.
The honest caveat: this only saved me because the snapshot existed before the problem, and because I'd practised the rollback once when nothing was on fire. A backup or snapshot you've never restored from is a hope, not a plan. But the discipline is cheap, the rollback is fast, and on Saturday it turned a reinstall into a coffee break. I'll keep doing it.