100% cotton will shrink some, and not all fabric will shrink the same amount. Good enough reason to pre-wash?
I have found that I minimize the ironing needed by setting my washer for SLOW spin, then hanging fabric on the clothesline with pins every 10 - 12". Newer fabrics tend to wrinkle a lot less than older cottons. (I occasionally am given a piece I know is old by the 36" width -- they always wrinkle a lot more!)