Drywall squares are useless for fine woodworking. One drop and they can change calibration, if they were ever calibrated to begin with. They work fine for drywall where accuracy is only so important.
The Woodpeckers square vs a stamped metal square is night and day. having the ability to place it on the material flat increases accuracy, vs the stamped where you have to angle it to register off one side. It also allows marking to be easily made on all sides of the square.
For rough construction the stamped squares are what I use, and switch between an aluminum one and a steel square. When it comes time to build to higher tolerances the Woodpecker squares come out. I have the 26", but after using it the 12" is on my short list. Unfortunately I prefer metric so I always wind up with two of everything since I also need and mostly work in imperial here in the USA.