I know that people used to rarely wash their quilts. They sewed a layer of flannel over the top, about 12". Where the quilt would touch the head. Then they took that off and laundered that instead of the whole quilt. The quilts were hung on the line to air out. I believe most of these had heavy wool batting inside. I remember seeing this when I was growing up. The actual quilts really never got dirty, just the area of flannel. They would be hung on the line and then whacked with a wire beater. Do not know the technical name of the "whacker". (I think maybe rug beater) This removed any dust that had accumulated on the quilt.
It was used on area rugs too. They were hung on the clothes line and whacked to get the dust out. Gosh that must date me--grin