Learning the curriculum up to black belt is one thing. Understanding how and when to use them is completely another. The longer you do something, given that the practice is as close to perfect as we can get, the better you should be able to do it over time. We've often joked about how interesting it would be if people showed up to a seminar without their belts. Would the higher grades still be recognizable from the beginners and/or intermediates ? If they aren't, then perhaps one needs to look at what and how things are being taught in their school.