Busch was too busy to be a pedagogue in the mould of Leopold Auer, Carl Flesch, Ivan Galamian or D. C. Dounis, and he resigned his masterclass at the Berlin Hochschule too soon to make his mark there. Only Dea Gombrich and Blanche Honegger were long-term pupils but he gave lessons to such violinists as Helen Airoff, Gosta Andreasson, Georg Beerwald, Frances Brockman, Alphonse Brun, Hermann Diener, Ernest Drucker, Stefan Frenkel, Arlie Furman, Stefi Geyer, Frederick Grinke, Gerhard Kander, Otto Kirchenmaier, Willy Kleemann, Elisheva Kramer, Dolores Maass, Frances Magnes, Yehudi Menuhin, Erica Morini, David Nadien, Bjorn Olafsson, Anna Radnitz, Ulrich Strauss and Charles Treger. Flesch thought that Busch ‘must be considered more of a suggestive influence than a real teacher’; and Boris Schwarz wrote:
Busch was not a teacher in the accepted sense of the word; one could take him as a model, but he himself could not develop a tender talent.
Grinke, who had lessons from Busch and Flesch, was left with strongly contrasting impressions:
Flesch was like a doctor – if something was not right with your technique, he would give you a pill; and if that didn't work, next time he would give you another pill. I would get inspired sometimes by a performance by Flesch, because of something in the way he played it. With Busch it was something in the spirit of his performances that thrilled me. He talked about projecting the music – he did not talk much about technique.
Joseph Segal moved in his mid-teens straight from one of these masters to the other:
After three years of Flesch, it was quite a relief to go to Busch, as Flesch had concert-like lessons – there was no privacy. Class teaching is all right within reason, but with Busch it was more human. He was a marvellous man in his own way, a very straightforward kind of individual, though he did not do all that much different from what Flesch did. He had certain opinions about Flesch's teaching, but in the meantime Flesch had changed his mind! I thought Busch was extraordinarily good on the musical level.