I think I would make them all different, but use dark scraps for the center lines and ligher ones for the outside, plus the 4 corner squares in the alternate block, or the opposite, light and then dark. I think if the rest of it is scrappy, but the alternate block is constant, it would draw your eye to just that part, know what I mean? I'm by no means an expert, but that's how I personally would do it :)