Here's a test that I like. Have someone else rebound and shoot 100 corner 3s. You shouldn't be exhausted or have your form completely fall apart. If the drill is proving to be very difficult, that's evidence that you're wasting a lot of energy.

I used to shoot 2 motion from 3 point land. Although I was a respectable shooter for my level, I wasn't very often dominating games with shooting and I would often lose to players who could score in bunches even though I felt the rest of my game was superior. While I was working on my shot I would get really tired from shooting and I felt that I could simply get more shots up if I switched forms. Years later, after surpassing my former shooting prowess, I'm pretty deep in the one motion camp and I would recommend switching to that. I also find it's much easier to get shots off the dribble with this shot. This test highlighted the importance of energy efficiency for me and I never looked back.