The tempo discussions by Mahgister are interesting. I heard Ricardo Muti give a talk from the podium that must of have gone about 15 minutes before the start of a work where he essentially makes the same points. It was difficult to understand him in the large concert hall, in his mixture of Italian and English and I remember thinking wouldn’t it be great to hear him give a master class in conducting and perhaps use a few examples.
I have heard many people look at film of Furtwangler conducting, critique his beat as imprecise and approximate at best, and wonder how he achieved his results, with his supple ebb and flow. He had to be the antithesis of George Szell, about whom his players would say “Even the spontaneity is rehearsed” yet Szell was reportedly a huge admirer of both Furtwangler and Toscanini.