I remember when I first met Jason Reitman with the 'Whiplash' script; he quickly became a mentor figure who guided me through the process and also protected me and made sure that when it came time to actually make 'Whiplash,' I was able to make exactly the movie I wanted to make.
It's certainly no coincidence that big bands became the entertainment of the army in WWI and WWII, and that jazz drumming style is very military influenced. The snare drum comes from the military and becomes the core kind of sound of jazz drums.
The end result of my personal story is that I became a really good drummer, and I know myself well enough to know that I wouldn't have without this really tough conductor and this really cutthroat hostile environment I was in.