I pre-wash everything, one yard or less in the sink, soaking in Dawn if necessary. If necessary, I use Retayne to set the dye, which happens quite often. One the rare occasion that Retayne doesn't work, the fabric is discarded.
My experience in Project Linus: A lady made a beautiful quilt top of bright colors, which she handed off to another blanketeer for quilting. After quilting and binding, the quilter washed the quilt. The bright colors bled onto the light colors. Both people felt awful. And the quilt looked terrible.