I have seen some systems do 15 passes before completion. Depends on how bad the fragmentation is. Consolidating free space seems to take the most time. Your 24 passes is a record breaker!
So no, no evil Hufflepuffs mentioned, but this doesn't mean they didn't exist.
@Pizzaconecake An Evil unicorn can be worth a kangaroo but the evil unicorn is rarer, older, more valuable, better than kangaroo. If someone accepts your offer for an evil unicorn then your lucky, they're overpaying.