The guy who installed drywall for me put a narrow 1/8" shim on studs on either side of the stud where a butt joint fell. This raised the drywall, by 1/8", 16" on either side of the butt joint, with the purpose of allowing the the butt joint taping to fill in what becomes a wide tapered area and level into the raised areas. So the butt joint actually becomes 32" wide, or wider than that if you consider where the drywall starts pushing up on the far sides of the shimmed studs. I suppose it helps make the butt joint more invisible. I could not find any direct reference to this technique, and no construction people I talked to heard of it. It seems to create problems such as at the perpendicular tapered joints, which no longer match due to one sheet being raised and the other not. So I've got one side of the tapered joint 1/8" higher than the other. I also wonder if it is better to have the drywall laying flat against the studs, and not at an angle on some. There also must be some stress by the screws where the drywall is starting to be bent. Has anyone heard of this technique, and is it a good technique? I feel like unscrewing the sheets and removing the shims before I start taping the joints. Thank you.