Moves you just can't do?

Anybody else struggle with moves in BJJ? We were working on the Berimbolo for a while before my injury but even after 4 months of working on it, a lot of us were no better at it than when we started.



What moves to you struggle with in BJJ? When do you say "look, this isn't worth me spending more time on, it's never going to be part of my game"?