I'm a big believer in prewashing so don't allow for shrinkage. When I refer to having 2-4" extra all around the quilt for the back, that's for the "shrinkage" that occurs from having tucks in the fabric, not from the effect of washing.
Other people want/use the shrinkage to achieve a look.
We each have a desired result. My quilts are typically puffier and less quilted than currently popular and I'm ok with that
