We can't say, "With the shelf at X-location, the bow shoots really sweet." because there are other factors that are equally or more important.
I've learned that I prefer how my bows feel and act if I keep some of those factors close to one another. Bow center(and static balance point), dynamic fulcrum/balance, string hand fulcrum, shelf. However we decide for ourselves, it benefits us to know where they are and why, how to coordinate them and balance them with the strengths of the limbs.