When I was at school (hundreds of years ago) we were always taught to roll pastry in one direction only,and not to roll it backwards and forwards. I have always done this but have noticed on many of the cookery programmes I watch that no-one else seems to do this. I just wondered what other people do,and was anyone else taught this.
I too was taught to roll pastry like that, and still do. Something with the stretching of the gluten and flour I think so that it did not shrink too much when cooked.