I went to a lecture in the past where Harriet Hargroves mentioned that she doesn't wash but knows that there are many experts who do wash. She also explained the whole bleeding thing by saying in a nutshell that it's not the fact that a fabric may release color/dye but it's how the other fabrics in the quilt react to that color/dye. Sometimes the combination of fabrics has one that will release color and another one will pick it out of the water so to speak and it ends up depositing on the second fabric (the one that is not bleeding)...if you combine the same bleeding fabric with one that won't pick up the color then it won't matter how much the first one releases color it just won't cause a problem. She says that she does tests on pairs of fabrics if she wants to be sure.
She also discussed things like the soap/detergent combined with the water you use may or may not cause the color discharging. If she still does the lecture it is really worth the time to listen.