I absolutely think that is true, in that the way it rides on your body has to be set every time. The pack doesn't land in the same place, or return to your personal "zero" every time.
Loosen waist, shoulder straps, load lifters, and when you put it on, always do it in the same order/process setting those (belt, shoulder straps, load lifters). Load lifters can make very small adjustments in how much load hits the top of your back vs front of chest, with extremely small changes. By loosening every time, once the weight is set on your hips and your harnessing is in the right place, then you just bring that bag in towards your upper back. Fit can really change with small amounts of foam in the lumbar pad (and where in that pad) as well, and how that thing can stay parked as you move.