Dominant Eye
I guess I'm a bit thick or slow when it comes to figuring out why things happen.
For about a year (the time I've been quilting) I just could not figure out why my piecing seemed to be just a bit off when I would finish off a strip of say, blocks. That strip would always measure just a little short.
Today I decided to place my guide on the opposite side of the needle, after sewing along my guide line on the other side. The first thing I notices is that the width of the space between my stitching and the guide line was noticeably different, This leads me to believe we have a dominant eye. For a year, I had always lined up the guide line to the right of the needle. Now I know that my true 1/4 inc seam allowance is 1/4 inch when I put the line on the left side of the needle.
No more 1/32 or so inch extra in that seam allowance. Now maybe I won't have any problems when I decide to make a built from a kit.