I have been adding sleeves to a bunch of big quilts because they're required for my guild's quilt show. I also added them to some smaller quilts because I think wall hangings should always have them (but I usually forget them until...) I gave away a bed-size quilt recently and removed the sleeve first, since I didn't think the new owner would ever need it. It is easier to put it on before the quilt is bound, but then you really can't take it off, and like others said, it's better if the sleeve is a bit lower.