While you are waiting, take any Bach 2 part Invention and play a few bars, hands separately, and turn it into an exercise. Play at different dynamics, with different groupings, staccato, legato, hold down all the fingers where possible, etc. This will kill several birds with one stone while you are waiting for Dohnanyi!
Thanks for your commendation. I have a thing for piano exercises and pure technique practice; I have this inescapable feeling that they're all worth doing in the long run, despite what certain experts like Chang, Bernhard, yourself, and many virtuosos say.
Gina Bachauer studied with Rachmaninoff, who is considered one of the greatest pianists of the entire 20th century, and she said he did Hanon daily "because he believed in the Hanon exercises so very much." If Rachmaninoff believed in doing at least some pure exercises every day, then that's good enough for me
My long-term ambition with all this technique stuff is to play my way through pretty much all of it at least once, then boil it down to a smaller and more manageable number of things, or a schedule that I can play a small part of every day. I mean in addition to the usual scales and arpeggios: Hanon, Pischna, Liszt's exercises, Dohnanyi.