I don't prewash either, unless it is flannel, that is a whole different story. I try to check deep reds to see if they run. I wash all my quilts that are going out as gifts before they leave my hands. The only things I have not washed are a wall hanging or two. Anything that may potentially be washed by the new owners or me gets washed after it is finished and the label is on it. I love the look of how is shrinks up a little.
It helps that I have one of those large front-loading washers and can fit even queen size quilts in there with no problem.