I make mine using 7/8 ribbon and when I want more ruffle I cut it at 18 in or 14 in for less ruffle. Also I don't sew mine when I'm done gathering I just tie the ends of my thread together, I also use embroidery thread to do the running stitch, normal thread doesn't hold very well for me . It does depend also on the ribbon. HTH
Ill try to post a pic of mine later today.