The only fabric I buy at Wally World for quilting is licensed stuff or stuff for a kid's blanket. For instance, I bought a bunch of yardage to make a quilt, curtains and pillowcase for my cousin's daughter - Strawberry Shortcake. I didn't worry that it wouldn't 'last' because she'll grow out of the Strawberry Shortcake phase in 3-4 years anyway. Meandering on a quilt takes no time at all and she feels special having her very own custom quilt and curtains. WW is also the only source, not online, for double napped flannel - used for making cloth diapers.
The service I get at the local store is very good. I have no complaints there. Walmart has a good deal of competition for fabric/yarn in my area, so best not to tick off their customers. At the other Walmart, they have no service - the fabric they sell is premeasured and tagged. I've never found an employee actually assigned to the area.