I don't think sewing on the side borders first actually "saves" fabric because the area is the same (sq inches). But, putting the border on the longer edges first (whether they be sides or top/bottom) makes better use of the fabic. Like others have said, if you put the border on the shorter edges first, the fabric needed to border the longer edges has to be longer by the with of the two borders already in place. Of course, if your quilt top is square it doesn't make any difference. I have done the math, matraina!
Originally Posted by matraina
I was told in a quilting class(and some day I want to sit down to see whether this is true)that putting the side borders on first saves fabric; appearance-wise, I don't think it matters.