As I have worked on customers quilt over the last six years I have come to learn that everyone has a different idea on what a quarter inch seam is.
I've seen some seams as wide as a half inch, but it is the "scant" seams and mismatched seams that cause problems.
When seams are sewn scantily... too scantily... often times the fabric threads pull and fray apart and leave gaping holes in the seams.
The same problem occurs when fabrics are not aligned and pinned together for sewing. The fabrics slip and while the seam is a quarter inch for the one fabric, it is scant or barely there for the second.
Another problem I often come across is when different size squares are sewn together (because they were cut inaccurately?). While you can pull and tug and stretch the fabric somewhat to make the edges meet, this can cause puckering in your quilt.
While I do my best to educate my customers and do some repairs to their work so that they are happy with the finished quilt....
Contrary to the song, there are some things that you just cannot "quilt out"