I'm a scrappy quilter mostly so I wash everything as it comes in the door. That way, I don't have to worry about bleeding or whether I'm mixing washed and unwashed. When I feel like putting something together I simply grab stash and cut knowing it will all behave in the same way. Even if it's a kit I wash because leftovers get trimmed up and go into stash bins. I have had bleeders and once is enough. I don't have the output of most of the quilters on this list, so for me having one quilt ruined after much thoughtful work is really too dispiriting.
Diana