I usually draft my patterns on 1/4 inch graph paper. When you do this and have half square or quarter square triangles, the finished product hardly ever fits the beginning design. Sooo. I set my needle to a little less that 1/4 inch and that gives some room for trimming if necessary. If you have a design with 4 squares across and only lose 1/32 of an inch, that amounts ot 1/8 inch which isn't noticable, but if you lose 1/16 on each, that is 1/4 inch which will mean that things won't fit.