If I’m reading your question correctly here are my thoughts. In regards to what I ask my drummers to understand in terms of theory (i.e. chord structure, keys, scales, etc. and keep in mind this for MS and HS kids) I admit I have them learn only the bottom basics unless they have prior exp on the piano, guitar, etc. I have all my non-drummer students learn all their Major and minor scales with jazz tonguing and 1-3-5-8 arpeggios. In addition, I have them learn all their Maj7, 7, and -7 arpgeggios, as well. From there we go onto the dorian and mixolydian modes.
As for the drummers, I want them to have a basic understanding of tertian harmony, but I’m more concerned with them focusing on independence exercises, basic grooves, etc. Ex. for our daily warmups I have the horns run down several of the scales/arpeggios while the drummer works on independence exercises – usually something from the John Riley book or Tommy Igoe’s Groove Essentials.
Past the independence exercises I have them listen to specific listening examples in an effort to help them to better their understanding of not only the role of the drummer in a band, but what that might sound like. It’s not that I don’t think they need to learn the theory, but I want my drummers to focus on drumming first and foremost. If they have the capacity and time to learn additional theory, then great!