answer:I never noticed that. It probably has something to do with the place on the cheque you’re holding on to. That matters a lot. Also, the embroidery (my cheques have that) with metal also weakens the paper. Here’s a little experiment, have two people hold one cookie at each side with one of their hands. Then, challenge them to break off a bigger piece using only their one hand. You will notice the person with the bigger piece actually used less force than the other person to break the cookie! Anyway, I think that example was used to explain that the more force you use under your fingertips (holding on to your cheque) vs. the lesser force (perforations), the more likely the cheque will crumble under your fingers.