If you REALLY REALLY wanted to throw a frisbee as far as you could, which shoulder would predominately think about? The lead shoulder or the trail shoulder.
Personally...
If I was thinking about a body part at all, I would be thinking about my spinningHips.
And once I got that Pivot activity relegated to subconscious control, I would focus on creating (and sensing) maximum Lag Pressure in my Left Hand.
And once I sensed Lag...
My focus would be on slinging that dadgum disc as far as I possibly could!