Hanzou
Grandmaster
I would expect advanced students to be "pretty much" in synch yes. But we weren't talking about "pretty much" in synch.
Just FYI; "Pretty much" means within seconds of each other. "Pretty much" should still be in synch.
A black belt in any karate school worth its salt should be able to perform a kata with proper technique, and at the proper speed. If you can't do that, you shouldn't have been awarded a black belt.