During my stay on Cake I have seen a few regulars on NL50FR playing with a 50bb stack and raising 5bb rather than 4. At first I thought they were bad players, but it turns out they're tight, regular winners. I think the reason for their stack size might be protection against set mining: with a $25 stack, if they raise $2.50, they're committing 1/10 of their stack, which makes calling with a small pp profitable only if you can stack them almost every time you flop a set, which is less than likely. And you can't ever follow the call20 rule against them.
PokerStrategy teaches you to play either full-stacked or short-stacked, explaining it with a graph (which I can't even find anymore) that shows how your EV drops when you play mid-stacked, though with no further explanations. But the system above seems to work for those players, and come to think of it I can't really see why it's a mistake to play that way. Is this kind of strategy somehow exploitable?