An old teacher of mine once told me a story about a drummer friend of his whom he called Hunchback. The reason why was, besides having terrible posture, when he played with his right hand over his left (in standard rock formation) his right shoulder was significantly higher than his left. Apparently, he eventually became deformed that way.
I didn’t believe him, and disregarded that mythical tale about crossing your eyes, and the one about your hands becoming hairy. What I think he was trying to tell me was: don’t slouch, and more importantly, don’t let the right hand do all the work!
After years of playing every night, after the show, my right arm would be crazy sore while my left arm was fine. Of course I refer to right-handed people – “southpaws” should cross their eyes and stay that way.
Anyway, after awhile, I started going out of my way to play stuff with my left (snare) hand. I would try to do things like crashing your first cymbal with your left hand, doubling up on your hi-hat and snare fills with only your left hand. All these things improved my playing dramatically and helped me become more ambidextrous.
One of my all-time favorite drummers, Billy Cobham, is neither right nor left handed, because he plays his hi-hat with his left hand, snare with his right, then flips it and plays his ride with his right and snare with his left. Sick.
The following exercises should be played to the correct BPMs and never with two hands on the snare. By the way, one out of the four exercises is a joke.