I honestly believe that when they shoot a free throw, they spend TOO much time CONCENTRATING when they shouldn't be.
Free throw shooting is almost like an automatic jump shot. You see, when you're playing a game and given the ball you'll shoot without thinking.
If you're at the freethrow line, you give yourself TOO much time to CONCENTRATE with NO pressure...then "BRICK"!!!!
Freethrow shooting should NOT involve TIME to shoot a shot. Once you get the ball, just shoot it as if you're shooting a jump shot (without thinking). It's to simply feel your shot.
Do you guys/gals understand what I'm saying?

.
I think you are over-simplifiying it too much.....you need to concentrate at least some.....but you are right thinking too much about it can ruin shooting rythym.