I've heard both ways. If I was going to be using the quilt for a child and it was going to be messed around with a lot, I wouldn't do them open because you don't have the strength you would have if you put them to one side. All you'd have is the seam threads holding it together and they can break if you have someone jumping on them and playing, whereas when it'd done to one side you have more strength.
If I was just doing a quilt or table runner or wallhanging for decorative purposes, I'd be tempted to do them open.