Plus as was already stated Luke learned some tricks without any training as well. Who taught him to pull the Lightsaber out of the snow in the cave on hoth? Sure wasn’t Ben. All Ben was shown doing was shooting at him with a remote, which he also seemingly picked up blocking on his own with Ben just giving some general musing about reaching out and such. And he sure seems to have picked up quite a few skills by the start of Return of the Jedi that he didn’t have any the end of ESB and as far as I know he never went back to degobah for more training.