Enabling BTRFS quotas can cause issues on some systems. This is rare, but this feature is disabled by default for this reason. Enabling BTRFS quotas will allow far more accurate tracking of free space on BTRFS partitions.
Deleting all snapshots is not a good idea if you are currently encountering any serious bugs on your system. If your system is operating properly, then deleting all snapshots should not be particularly risky. Just be sure to take a new snapshot before performing any changes to your system such as installing new programs or performing a system update.
Yes correct, cause it needs to meet all the conditions before it removes something.
So for example lets say you have set 2 snaps for 1h but actually there are 3 now cause you did a new run in the same hour.
If that oldest of those 3 matches as well the other conditions of snaps it will be removed and you end up with 2 per hour again.
All conditions needs to be met before something is removed that’s why you end up with 16 snapshots in total ;). Thats what is a called a retention policy.
The numbers you have defined in your screenshot are the number of snapshots which will be kept when the Snapper cleanup job runs. You will continue to accumulate snapshots normally (according to whatever configuration you have defined) in between the cleanup jobs.
By default the cleanup job runs once per day, but if you wish you can change the schedule to run more or less frequently. See this comment for example: