My reaction was the same as yours when I first heard of a scant 1/4". Mentioned it in a class one day and the teacher explained that it allowed for the turning in the seam. Still didn't think much of it until I was making a quilt with lots of strips that had to fit inside these inside a frame. Nothing was fitting properly so decided to give the scant 1/4" a go. Like magic everything just fell into place as it should. I've used it ever since. I put a piece of masking tape on my machine then adjusted the needle. Just check the measurement from time to time. Trust me it does work.