You know, I'm against "three strikes and you're out." It's too expensive and doesn't deter. But the case could be made for "20 strikes and we'll lock you up till you're 50" (admittedly, it lacks a certain jingoistic ring). But seriously, at some point you do have to keep "them" (people certain to offend) away from "us" (everybody else).
The Times reports on a robbery and attempted murder: "Mr. Milton and Mr. Louree are both from Brooklyn and have previously been arrested more than 20 times each." They don't really need another chance.