I use the number 2 setting. I select that size because it is the size my machine prefers quilting with a walking foot. Doesn't matter what I prefer. LOL I have little to none tension and thread problems using that that setting when machine quilting. For free motion quilting it is 0 setting and the slowest sewing speed setting with size 90/14 topstitch needle using 40 wt poly thread in bobbin and top. I seldom have thread or tension issues.