It depends. Usually my pieced back is fairly simple and while the quilting pattern may not be specifically in place to accent the backing, it looks fine and adds interest. I don't tend to do very rigid motifs, though; I'm much more of a doodle-style improv FMQ. I can see where it might not be most pleasing if you have a complex feathered medallion showing up in an odd place on the back, for example.