I put my ruler line on the outside of the fabric edge. Just that teeny bit of extra is important enough to matter. Honestly I use my Go dies for 99% of all my cuttings. Have you tried sewing pre cut squares (charm pack) together to check your 1/4 seam? I mark my 1/4" on my machine with tape or some other edge at least 4" long. No way I can sew a straight seam without a guide.