Duke William of Normandy won the battle because was well prepared and had a good army. They prepared carefully for the battle. The Normans had knights on horseback who were skilful fighters.
A utility knife, metal ruler, and a hammer can be faster than trying to carefully saw an opening. Score the drywall a couple times till you are most of the way through, then just knock a hole with the hammer and break the drywall back at the score lines.
Cutting drywall. To cut a straight line in a sheet of drywall, place a straight edge along the guide line, and score along it with a utility knife. Fold the sheet to snap it along the line, and cut through the paper backing.