I normally buy extra, but I do like to get the measurement I pay for. We have one LQS around here that regularly shaves its fat quarters -- 17" wide and sometimes only 18" instead of 1/2 WOF. They do a lot of scrap sample quilts and I suspect they take the extra from the 18" dimension for their scraps. I don't buy fat quarters there unless I measure them first -- and no the owner does not like her fancy folds undone.