You have "discovered" a fact that most instructors try to get across to their students but it doesn't "take" until the student is ready.
When you practice on form -- practice on form!!! NO TARGET!!!
Once the form is automatic and the same every time, or almost every time then and only then start with a target. Shoot concentrating on the target and FORGET FORM. When or if you become inconsistent on the target, take it down and go back to form work.
This is really well pointed out by Rod Jenkins in MBB3. And this doesn't apply to just archery. All the really good performers in any sports discipline work on their form, but in competition rely on subconscious form programming and only concentrate on the "target".