Interesting about the judo instructor. The great thing about judo is that practitioners test their techniques on fully resisting opponents. This is why Kano’s judo students could beat traditional Japanese ju jutsu students who had far more “deadly” techniques, because the training was so much more realistic. BUT, as with most styles judo is extremely limited in terms of not training to deal with strikes, weapons, small joint locks, dirty tactics, etc., etc.. Any style is by nature going to be limited, and “on the street” where you can come in contact with anything, the holes in whatever individual style a person is practicing will eventually come to light.