I always butt my seams, but, some days that isn't even enough. So rather than rip out the whole seam, I put a couple of stitches at the seams, check to make sure they are aligned and then sew the whole block. I have also tried pinning the seams, but had trouble doing that to. By just sewing a couple of stitches over the seam, the worst that happens is I rip out couple of stitches instead of the whole thing.