If your batting says you can stitch 10" apart, you should still consider what kind of use your quilt will have. If it is going to be washed frequently, I would stitch it closer - like 4" or so. My personal choice is not to stitch IN the ditch, but just beside it. This way if I wobble a bit, it doesn't show as much as when I wobble out of the ditch and onto the fabric. If you're not sure about stitching in the ditch or how far apart the quilting should be, just pick a spacing that you like and stitch that distance apart in straight lines. It will be wonderful what ever you decide.