I do not prewash and I wash all my finished quilts in my home top loader old fashioned lots of water washing machine with scent free laundry detergent (I make my own powder) with a couple color catchers and then put in the dryer. I've never had a seam come out or any bleeding. I mark with crayola markers if I mark, and use Elmer's washable school glue. If I give a quilt to someone I know they will never give it any special care so I don't either just to see what will happen. Many years and quilts later, nothing bad has ever happened. Maybe one day and I will be sorry, but so far so good. The only thing that has never come out of a quilt is some kind of chalk I used to mark my hand quilted queen sized. And I washed that in the washer and put it in the dryer. All good.