I used to work at a Viking dealer's inside JoAnn's.
When JoAnn's does their inventory each year, they weigh the fabric. They also have signs posted in the break room that says "Thumb mistakes are costly" with a picture of a thumb. You guessed it, they're not supposed to give even a thumb's worth extra.
Lower end stores like Walmart (don't shoot me for saying this) and Ben Franklin have, in my experience, had more 'partial' bolts than others. What I mean by 'partial' is there will be more than one cut on the bolt.
BTW I was at Walmart last night and it looks like they got in a lot of new fabrics most of which are running $4.90 and up! I think I'll be buying a lot less fabric this year!
Hobby Lobby's prices had already gone up by $1.00 per yard at the beginning of December but I haven't been there this year yet to see what's going on with their prices.
Peggy