Personally I was never happy with supervising the school when I was down to disappear off on long nav ex's.
Then there is the other days when you find out that you have been supervising, but knowbody has bothered telling you.
The issue with AIC's needs to be sorted as well. You have some very qualified examiner examiners, who state that you must follow the AIC's. And there others who say you don't have to bother they are only recomendations and have no legal standing but I would advise you to follow them. But of course in both cases the AIC apply's to everone but them. A bit like the differences training for different types of twin. I have yet to hear of a MEP examiner to refuse to test someone in a type they haven't flown before.
I haven't yet heard of any court cases which have set a precedent to which opinion is correct. The caa officially of course will say you have to follow the AIC. If you speak to the people informally they will say its a grey area which has yet to be tested.