Right. On a day where I'm really crushing it (which for me is Teebirds > 400'), I really only feel that I'm using my wrist. My hips drive, my arm slowly creeps past my chest, then it's probably 10" inches, or so (maybe less), of movement where the disc weighs a ton and I really only feel my wrist opening - the only truly active part of the throw that involves moving my arm/wrist. There's probably more going on, but that's what it feels like
On bad days, I feel like my whole arm's into it (because it is), and I'm not getting anywhere near the same distance. When that happens, I slow down, loosen up on my grip, and focus on getting that really heavy feeling in the disc again.