I remember one instructor used to give you a smack around the head if you did something wrong, it scared the cr*p out of me the first time it happened as we were doing a circuit and I was looking in the opposite direction from him. I have no doubt it sharpened up my circuit technique as well as improving my lookout to watch for his backhand.
The same instructor once bet that he could fly a better circuit than me without using his hands. He then went on to fly one of the most accurate circuits I ever had ever seen using just trim and his knees!
Stude