You could just give more time on tests such that it isn’t worth gaming the time limit. Aren’t we supposed to be teaching subject matter? Why do we care how quickly people can do it? If you’re worried about dumbing things down too much, make the actual content harder. Given how much grade inflation there is, I don’t understand why anyone would be gaming anything anymore anyway. And let’s be honest. Unless you’re trying to get a PhD, your grades don’t matter.