Now this is a very good question. But the answer is personal.
For me the penny dropped when i was around 11 or 12. I attended saturday morning classical orchestra sessions every week. I can't remember the duration, but it was one part section training then one part orchestra rehearsal. Our Percussion lecturer/teacher was an old school ex pro. When it came to Snare Drum he absolutely insisted that we ALWAYS place the snare on the stand with the release mech in the same place. Every Time!!! READ MY LIPS EVERY TIME! (that was him.)
Why? Because the snares were always disengaged when you weren't playing because of snare buzz. You then count maybe 200 bars or whatever before an important roll or passage then slip them on without having to hunt, execute the moment then slip them off. Move to the next thing.
Now heres the thing. He encouraged us to have the snare mech on the left side because a, it was easy for trad players and b, (at 6 o'clock) you wouldn't get caught up in your clothing fumbling around and then missing that moment that took 80 or 90 other players of the orchestra to build to.
c, as a righty kit player I can engage/disengage with ease with my left hand while still riding or filling on toms with my right.
So there it is, the left side it is around 9 o'clock.
Phew.