I wash one particular quilt monthly, if not more often. It's MY naptime quilt and it gets dragged all over - the couch, the floor, the terrace, sports events. It's over 10 years old, W&N batting. It's fine. I've also made kids quilts that were taken to school for naptime and washed weekly, and were still going strong a couple of years later.
I'm surprised you're seeing a difference in your quilt.