I have never made a quilt to actually be used as a bed spread. Mine are used to put on top on cold nights, or snuggling in while watching TV about...5 x 7 or so. Just depends on how I 'feel' about the fabric and what it looks like as I construct it.
There was one exception. My father would come home from work and take a nap on the couch. My mother would always scold him saying that he was getting the couch dirty every day. So, I made him a quilt that looked "old and dirty" (as my SIL said) that Mother put on the couch for him when he came home. Problem solved! He treasured it for years and was passed down to one of his grandchildren who were delighted with it, and amused by the story.