it all depends on dimensions along with, how well the box is built....if you double baffle it, put 45's in the corners, and make braces from the wood, it limits the size of box that can be made out of the full sheet
I've built many boxes right at 3.5 cubes net with one 4x8 sheet. Just have to plan out all of your cuts. Also managed to do 45's in the corners on some of em.