NASM isnt notorious for "full ROM". as a matter of fact, i dont know that ive ever seen anything in their coursework about a leg press. they do primarily closed chain exercises when working in stable environments. squats, multiplane lunges etc. i know alot of NASM certified trainers and all they do is advocate shortened range of motion, relatively speaking. watch a technically perfect NASM squat, and it'll get picked apart by athletes of many backgrounds. (PL, OLY lift, BB'ers etc)
btw, a 45 degree leg press with 800lbs on it is actually about 565.6 lbs via physics. angle is everything.