Surprised you didn't check whether it's actually square by drawing one line, flipping it around, drawing another line close to the first one, see if they are indeed parallel.
@@Lumbergh42 that's a good point actually. I've been reading about a lot of them these days being out. I'm currently in the market for a large plasterboard TSquare and many of the reviews I'm reading are terrible regarding the accuracy. It's a shame I missed it off this vid, but I'll check it out tomorrow and report back.
