I always stitch about 1/8 inch away from the outside edges of my top. The stitching prevents the edges from stretching and keeps joined seams from unraveling. I usually use a regular stitch length, but if my edge has any bias piecing, I will use a larger stitch so that it can double as a gathering stitch just in case a block edge needs to be adjusted.
My longarmer has told me that she really appreciates not having to repair unraveling seams on the edges of my tops.