Raoul Berger (who eventually had a fall out with the conductor Stokowski and left The Philahrmonic Orchestra) described Stokowski’s rehearsal process:

In rehearsal Stoki was given to the methods of a marine drill-sergeant, brutal and insulting.  In those days he was accustomed to make sweeping changes every season, so that those who were dependent on their jobs lived in fear and trembling.

He had his good qualities – a rich, voluptuous sound, great precision and vitality.  In music that called for fire and sensuality he was at his best.  His ‘Danse Infernale’ from Stravinsky’s Firebird was truly demonic, etched in biting rhythms.  He rose to sensual ecstasy inthe Afternoon of a Faun.

Unlike Walter and Mengelberg, Stoki indulged in no long-winded ‘explanations’ of the music in literary images.  All was addressed in terms of how to do it, as it should be.  Consequently rehearsals were short, not a minute wasted, often only half the length of the average rehearsal.  He knew where the weak spots were and rehearsed them. … Not a little of the ‘mesmerism’ of which some of his players speak grew out of the fact that the men were not wearied , boring rehearsals, that we had fewer concerts and rehearsals than most major orchestras, that often they had not a chance to play a work through, and therefore fell on it with ardor at the concert. Then too, he had his matchless players – Tabuteau, Kincaid, and Caston.  When he once adjured Anton Horner to play a passage softer, Horner, after several tries, rose, brandished his horn and said, “There are sixteen feet of pipe in this, and if I don’t blow in, nothing comes out.” That closed the matter.

Chasins, Abram (1979) Leopold Stokowski: A Profile.  London: Robert Hale, p.109.