I make a lot of charity quilts, so time is the decider on what I do. I fold the backing to the front and machine stitch it most of the time. Even if I use separate binding I like sewing it on the back and folding it to the front and then use a decorative stitch, usually the blanket type stitch, to sew it down. If I was taking the time to do an entire quilt by hand, then I would surely add separate binding to the front and stitch it down to the back by hand. But I have arthritis in my hands, so hand work is out of the question for me.