I wash it all. I have only been quilting for 7 years (retired teacher) but in that time I have learned...wash it. I have had blacks and reds bleed all over and ruined one quilt. So, I now use color catchers and wash everything when I bring it in the door. Yes, I was all pre-cuts, and lay them out when still damp and they don't shrink as much as the first ones that I did and lost up to 3/4's of an inch in many already "cut for me". So I wash them and if they shrink, then I change the quilt directions and go to as much as of up to 3/4" to make the fabric work and adapt the quilt slightly.