The RAF may teach a method to their cadets, because, they will be flying the aircraft for a matter of months before moving onto a high inertia aircraft, where the technique will be relevant.
Flying Scholarship cadets! Hardly Likely! One of the reasons was to ensure they did not go low on the approach and scare villagers and motorists on the approach path. Constant aspect=equals constant angle= correct glide path.
Personally I avoid even mentioning flaps for the first few circuit lessons
So what are you teaching them then? Remember the law of primacy, where students remember best, the thing they are first shown, so under pressure i.e. an engine failure, there is a high probably they will land flapless! In the UK/JAA syllabus teaching use of approach flap is in Exercise 8(ii) Circuits are 12/13.