It should not be taller than the top of the shoulders and the bottom should just rest lightly on the top of the buttocks. The width should not protrude beyond the waist more than an inch or so. At the top, the width should not extend beyond the shoulders. Exceeding the persons physical characteristics causes two problems. As jumpsuits become tighter and more streamlined, rig drag becomes more pronounced.
Problems arise if the manufacturer proceeds in the inverse design direction as well.
Making the rig excessively narrower than the body planform can result in an overly thick pack. This idea has been chosen by some manufacturers which create inherent problems. The end result is a very narrow brick strapped to your back. In addition, the thicker rig creates more distance between individuals during exit stringing the exit out. Ideally, the containers should match the body planform and be as thin as possible.