>I am now intrigued as to how instructors are trained to take account of individual learning styles<
I think quite a simple answer to this is very rarely!
There is definitely a psychology associated with teaching the circuit - as indeed there is wilth almost all instruction.
Firstly, it's essential that the student has seen a really good demonstration and in the early days, especially if a student is struggling, I redemonstrate a circuit every so often to a) give them a rest and b) give them a chance to take it all in again. I will often do a circuit demo on the first circuit of a circuit detail - all being well this will be a template of what I would like to see them copy!!
If in doubt I try to sit on my hands, zip my mouth up and let them get on with it - how many times have you made a comment only to regret it a short time later!
Another tactic is to do a landing and taxi back to the hold point - I take over to do the taxi and do a mini debrief as we return to the take off point. Probably the worst place to learn anything new is flying round the circuit!
I would never dream of throwing the whole lot at them on the first detail unless they had shown signs of being a superstar previously.
As has been stated previously we must assume that all the previous upper airwork has been properly completed - I find this to be rarely the case. Although I would be a supporter of doing dummy circuits at height I always get it across to the student that when they are in the real circuit the workload is higher and they will have to get on with it if they appear to be slow with the checks, etc.
I also teach them to conduct visualisation exercises at home - sit in your armchair and picture yourself flying the perfect circuit! Sketch the circuit out from memory and put down everything that you would do - show this to your instructor for comments - this can be very illuminating and spotlight misconceptions.
Hope this helps!