Jason Todd pulled the mother of all fast ones on him with one of the oldest tricks in the book and then beat his sidekick within an inch of her life.
It's not just fighting skills that Ollie was supposed to be training. It was also planning, preparation, emotional battles, psychological edge, right down to weapons maintenance and herbal medicine. I maintain that we've seen any of this come into play maybe once or twice since his return.
The capability of his enemy should not matter in least. Hell, the capability of his enemy is an excuse. He went to train in order to win his battles. He went to learn how to not lose anymore, and yet that's still all we ever see him do.