Most new homes use 5/8" drywall on the ceilings. With spans up to 24" and insulation above, the added thickness over 1/2" helps to prevent sagging. On walls, 1/2" works fine. When drying out a new home, some contractors wire the furnace to run non-stop. Drying the wood before drywall helps to limit the amount of cracking later. The day before drywall goes up, it's a good idea to show up with a dozen studs and replace the bad studs. Some wood when it dries will "pop", this is the time to replace them. Sometimes, on non-weight bearing walls, you can put several sawcuts in and bring the stud to straight if replacing is too difficult.
Notes on framing:
The camber should point the same direction on walls.
The camber should be up on floor and ceiling systems. When weight is added, it will bring the floors and ceilings down flat. Terry