This is a good example of "turning down the gain". When we tune control
systems we generally don't crank the gain up to the max and then reduce
it until the system becomes stable. We do the opposite: start with low
(zero) gain and gradually increase it until the system becomes
unstable.

Part of the confusion is that there are times when large control
movements are required (rolling into a steep bank turn) and times when
they aren't (flying straight and level). The student needs to be
clearly told, and told again and again, when each is appropriate.