There have been many posts regarding the thickness of the thread. You may want to check into that. I marked my sewing machine with 6 layers of painter's tape. There is also the hump that is formed when pressing the seam to one side. To resolve that problem, I cut my strips letting the thickness of the line be on the side of the fabric strip I am cutting. I use Omni rulers. My friend showed me this and even if that line is 1/32" if an inch, it has worked for me. But the most improved system that works best for me is EB method of over-sizing blocks. Can't be used with ALL quilts but over the years, I have been amazed with HOW MANY quilts it can work with. As LONG as your seam is consistent, that is the most important issue. If you do a Bargello or a Trip Around the world, if your seams are all consistent, your seams will fit snugly together. Good Luck