I honestly don't think it matters. My mom would take left over fabric and cut them into 2-1/2" pieces and sew them together and use up her fabric in the binding. I usually would get more than I need so that I would have leftovers. Everyone does something different. I usually like one piece on all four sides. That is my preference. I cut the vertical one piece long (make two) and horizontal one piece wide (make two). It is the finish part of the quilt and I like it finished with one long strip. It doesn't matter. Whatever you want to do is ok. I haven't had problems with the Roseville, Minn. JoAnn's. They are all quite knowledgeable even if they are not quilters. As a matter of fact, I made a horrific mistake by cutting some white on white which was going to be the backing and cut about six strips that was going to be sashing. I took it to JoAnn's and they immediately. They figured out that I had exactly enough uncut to make a one piece backing and still have fabric left over. My store is smart. Love that store!!!!!
Edie