I think the most important part of the shot is doing things consistently. If you do anything the same way long enough, it will become repeatable and you can put the shots where you want them to go. If you look at the archery traditions throughout the world, you will find many different ways of holding the bow and drawing the arrow. But I'm sure that each and every one of them requires that a person be consistent if he is to become accurate.
I think the reason Terry's comment works, is because it is easier to develop consistency if you use proper allignment. I think if you could learn to always hold your shoulders at a 47 degree angle to the target, you could learn to be just as good a shot as if you hold them at 90 degrees to the target. In fact, I think there are quite a few archers who learn to be good shots shooting with their shoulders open to the target, either because they physically can't shoot with their shoulders perpendicular to the target, or they just like it better that way. I've read that it's easier for some people to develop good back tension when they draw the bow with their shoulders open to the target.
I don't find that to be the case with me, and I try to model my own form as closely after Terry's clock as I can. But there are still a lot of ways to miss the target once you've drawn the bow with proper allignment, some of which are a loss of focus, a blown release, not hitting your anchor, yips, moving your head or not having it in the same position with respect to the arrow from shot to shot, slight differences in your bow hand or bow wrist position, how much you bend your bow arm elbow, whether a shoulder is up or down, etc. etc. All of which comes down to consistency.