Lots of waste on drywall, but it is recyclable. Each 4X8 drywall piece has slight indentions at the end sides so that you can apply the fiberglass tape and put mud over the tape without creating a rise. Even with sanding, if you don't line these indentions up, you will get a slight bump in the wall along the seam which is very visible if the light hits just right. That is why there is so much waste, because you don't want to line up pieces that don't have the corresponding indented portion.