I got taught bad weather circuits (low and slow, from which I'm clever enough to work out how to do them normal height and slow). I even did some the other weekend.
As an instructor I have to also consider and teach people who arnt that clever(a recent FIC candidate was aghast that I wanted him to slow to approach speed downwind to avoid extending downwind over a built up area)
Most PPL's will never need to fly a bad weather circuit but there will be many occasions in a circuit where it would be best practice to slow down.
Slow flying is part of the PPL but to take if from a box ticking exercise it has to be taught as a practical exercise and slowing down in the circuit for spacing is its greatest practical value, followed by weather and precautionary. In fact teaching spacing in the circuit is rarely done and the approach go around is usually the end result and caused by poor spacing and lack of forward planning.
The other thing that would help is if more pilots used the base leg call when appropriate. Yes I know its an on request call but if you can move away from the confinement of flying by numbers you can start to actually develop some CRM, SA and ADM skills. For instance if you are on or about to turn base and are not sure of what is ahead or out on final why not call, "base leg". Why keep a secret?
The other help is if pilots would follow the correct procedure and actually call final after making the final turn rather than delaying it because of traffic ahead or other folklore reasons.