I think it should be based on both experience and LBM, not total BW. Someone who weighs 250 but is 35% fat, won't need near the same stuff as someone who is 250 and 8% fat. Even though both are the same weight, their caloric needs are totally different. So, I would assume that their supplementation would be different too. I like to base things on LBM personally. I do it with protein, cals and other stuff. It's worked out for me pretty good.