Do whatever you want. I don't do stitch in the ditch because i don't like stitching thru all those seams and i think it's harder to get a good looking straight line. I come away from the seam anywhere from a smidge to a 1/4". I am currently working on a disappearing 9-patch and opened those seams when i pressed to maintain the accuracy. (That and the fabrics are all darker, so you don't see the seams)
I know when i use whites/creams, i always press the seams to the darker side i don't see the seam fabric.