I was not a quilter, but a sewer so I took a class for six weeks to learn how to piece a quilt. I made a queen size quilt in six months from start to complete finish on my home sewing machine. The teacher taught us to use a scant 1/4 seam and it killed me. I was used to 5/8 seams and that scant 1/4 seam was a killer for me. I ripped out every single thing I sewed because when the block was finished, it was too small. The scant 1/4 seam does make a difference because when you press your seam, it takes up room. I had to move my needle over to get that scant 1/4 seam but then I would turn off the machine and it would go back to normal needle position, so I finally learned how to do that scant 1/4 seam. I have no clue where it came from but I do know that on my vintage quilt tops, they used the scant 1/4 seam too so it has been around quite a while. It definitely affects the block, measure yours and you will see the difference.