I use the scant 1/4" because I find it helps with my accuracy. For instance, I'm currently working on pattern-testing and making a shop sample. The quilt has flying geese and the instructions are the old sew-a-square, flip, trim, sew-another-square, flip, trim for the flying geese. If I sew a true 1/4", the corners are short. But if I sew a scant 1/4", the corners turn out perfect.