For over a decade, I've been developing documents like this for use in private lessons. They aim to break down specific musical concepts and technical challenges in a methodical way. Hope you find them helpful!
If you're a current student of Charlie's, you can download materials for lessons here.
If there's a topic that you'd like to learn more about, or are looking for something specific, drop me a line!
Some recommendations from the wide world of published methods for snare drum/drum set study.