I also have a 1/4 inch foot for my Janome. I always thought I was sewing a perfect scant 1/4 inch seam. I am making an optical illusion quilt by Erin Underwood. It needs to be really exact. Luckily I checked my accuracy before I started. I needed to move my needle 2 clicks to be accurate. I finish the quilt you sew 48 wedges together to make a circle. If you are a little bit off it will make a huge difference and it will be a mess.