Back in the day when I was training in London during the 70s, group teaching was considered a cheaper, lower grade version of learning Alexander's discovery. Some people still think this way. This wisdom is premised on the idea that giving pupils’ an experience is king: what you are teaching is a sensation.

I agree - when your primary means of education is first to deliver an exceptional experience, then prolonged physical contact with a pupil is pretty much essential. This in turn leads to a world of “hands on” and intensive one on one teaching.