Contractors come in and want us to get a forklift to load maybe 30 sheets of 4x8x1/2" drywall. But it has to be hand-loaded into their pick-up truck anyway so we just throw 15 "lifts" on a cart in about 60 seconds as they stand by amazed and then wheel it out. Now 5/8" is a different story. That stupid 1/8" makes it 'twice' as heavy.Glue it to the studs and you really have a strong structure. Yup, drywall should be glued to the studs which eliminates a lot of fasteners so taping is quicker but also the glue keeps the board from getting concave where the framing isn't quite perfect. If you wanted to make a really non-resonant 'wing' to substitute for a corner I would suggest 5/8" board glued to a 2x4 frame with 30# roofing felt glued to the back of the board between the studs.