I agree with the erstan947. you do what works for you. store bought binding is not the only way to go. I guess she has never put a quilt in a quilt show. I have and my own binding was fine. you do what you want. when I quilt my own I dont scrunch I roll. I feel when you scrunch you stand to much of a chance in shifting the backing. so as I quilt I roll and put and keep going. good luck to you.
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Delta