It’s said that an Olympic Wrestler doesn’t use a single move in the Olympics unless they have drilled that move at least 10,000 times. Nothing is different in any of the martial arts. If you want to throw a Oomapolatta against a black belt you better have drilled that move a few thousand times, otherwise he’s just going to pass your guard for all your trouble. While there is no replacement for sparring and live grappling, drilling is twice as useful. For every hour spent grappling, you should be spending 2 hours honing your technique, speed, conditioning, smoothness and power in every movement.