I've had plenty of practice

True, but has said voluminous practice actually done you any good???

The White Knight totally "went Rain Man" on Alice when he huffily told her, "Oh, I've had plenty of practice --- plenty of practice!" after she expressed concern about how he kept repeatedly falling off his horse, so perhaps he (and the Red Knight, as well!) was just super-clumsy, and thus no amount of training could significantly improve his horsemanship.