"How do I know I had a crossover problem?"
I'm a right handed, 2 eyed shooter and my right eye is getting weaker. So on left hand birds on posts 1, 2 & 3 there are times when the left eye takes over and I tend to shoot 3-4 feet behind the target. I won't stand here and tell you that the "hooded sight binder" cured that problem completely but it has helped to cut the number of instances down considerably. I DO NOT bead check, but have to make myself be a little more patient when shooting left hand targets from posts 1, 2 & 3.
It does help.....small investment for a 95% cure.
PS Bill and Matt...your pics always come out looking great. I need a lesson from you guys.