As a former fabric store employee, I have to add my two cents. Sometimes they are stuck between a rock and a hard place. Where I worked we were instructed to allow a pencil width over the line, but that is NEVER enough to adjust for the fabric being stretched and twisted on the bolt. I always tried to err on the side of the customer. So I usually allowed a couple of inches, but still not usually enough. And we were NOT permitted to tear the fabric. A lot of fabrics come from the manufacturer in such bad shape. In order to ensure every customer gets what they pay for, the store has to literally give away fabric that it has already paid for. My thinking was that it was better to lose a few pennies and have a happy, loyal customer. Sadly, it was not always just the inexpensive fabrics that came in this way. I worked there for 4 years, and the quality of so many of the fabrics just seemed to go down as the prices went up. When I purchase fabric, I have just learned to buy a little extra for squaring up. I'd rather spend an extra dollar or two in the first place, than to run short and have to go back only to find they are out of it or the dye lot doesn't match.