That wouldn't address my use case, because the machine in question spends nearly all of its time at the school (I normally leave it there when I go home). Furthermore, there are plenty of times when it's OK to back up even when it's at school, because I only use it in certain classes. Forbidding backups in the school zone would result in perhaps monthly backups instead of daily backups.
In fact, my use case could also be addressed with a blacklist approach, where backups at certain times are forbidden, and all others are allowed.
That wouldn't address my use case, because the machine in question spends nearly all of its time at the school (I normally leave it there when I go home). Furthermore, there are plenty of times when it's OK to back up even when it's at school, because I only use it in certain classes. Forbidding backups in the school zone would result in perhaps monthly backups instead of daily backups.
In fact, my use case could also be addressed with a blacklist approach, where backups at certain times are forbidden, and all others are allowed.