So, positioned vertically, each sheet of drywall board will completely span two studs. Also, the two vertical edges of each sheet will touch two more studs.
These edge studs are important: drywall seams must fall on the centers of the studs. So, the edges of two sheets of drywall will share one stud. Each edge must have a solid resting place. No edge should have a hollow space under it.
Finally, note that the drywall breaks over the middle of the door opening--not at the corners. Corner breaks present two problems. First, the opening and closing of doors (and windows) will eventually pry apart the drywall seam. Secondly, bulges resulting from the finishing of the drywall will interfere with the installation of door trim.