3 on 1 is bad. 1 on 1 is the standard in Australia. Seriously I can't see how it can be done 3 on 1.
I watched them a few weeks ago. First the student sits on the beach with a little kite+harness and learns how the kite moves with the teacher sitting behind them. Then student moved to a normal size kite and in the shallow water again with the teacher just behind them yelling left,right,down,pull etc etc as the student gets dragged along by it. Rather amusing
Then they get a board and they try to get moving. All the time I cannot see any room for another student let alone 2 without the teaching process taking a lot longer.