He has a mind palace/photographic memory, so memorizing everything on the test won't be a problem for him. Plus, knowing Sherlock, he'd probably give the guy ordered to make sure you don't cheat laxatives in his cereal, and then replace him as a substitute lol But in all seriousness, I agree that he might not be the absolute best, but hey, I think it's a better shot than most would have at it.