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.
Again, it's likely that you will have to cut some pieces of drywall in order to center the end pieces onto a stud. 1  When cutting drywall, use a T-square and razor knife to score a line on one side of the drywall paper.