anything less than permanent is kinda useless. the kind of person who breaks rules, knowing that it's against the rules, is unlikely to come back in a day completely willing to follow the rules
I guess, when it comes to rules that are a little more "open to interpretation," it might be reasonable to use shorter sentences. but in that case, breaking the rule is mostly a mistake, and I don't really see any reason to punish them for that at all, if they're willing to behave from that point on