Xtol is typically only diluted when it is to be used one shot, dilution is at-it's-root a way to reduce cost. Dilution also can have side effects that people like.
In systems that are designed to be replenished Xtol is not diluted. One just follows the directions for replenishment guidelines in Kodak's instructions. Over time the full strength Xtol gets 'seasoned' and the side effects people like about dilute Xtol 'miraculously' happen even without dilution.
Replenishment is also very frugal, reliable, and easy.