I started out washing all my fabric as soon as it came in the door. I later realized it was way too time-consuming for me. i stopped cold turkey and never looked back, using pre-washed and non-washed together without paying attention to which was which. I have had zero problems and don't regret the decision. I do toss color catchers in when i wash the finished quilt. If they "catch" a lot, I include a box of color catchers when i give the quilt away.
DebD