I have changed to pressing seams open also. It has improved my piecing 100%. I stick a pin straight through where the stitching is, 1/4 from the edge. Then making sure the pin is seated perfectly straight (not tipped up or down) in both pieces, I put a pin in the right seam allowance. I sew right up to the pin when stitching so the left half of the seam is anchored. Remove the pin and go til the next one. Not as tedious as it sounds....but if you hate pinning this method is not for you. I get a group of blocks ready then sit in the recliner in front of the TV and pin as large a group as possible. You must treat the blocks gently though or the seams will come unstitched at the edge. As long as it isn't more than 1/4" you are ok. I use a pretty short stitch length when sewing.