I have a superfly set-up with a continuos ridge line. The tarp is attached by two small s-biners to prussics on the RL. One of the s-biner to prussic connections has a short loop of shock cord in the middle, acting like a self tensioning guy line.
I can't remember where I read that the loop of shock cord should be used, but it has been on my tarp since I set it all up. I'm noticing though that to get enough tension in the silnylon, I'm stretching this loop to its limit. Do I really need it? I think I will get a tighter pitch without it, but don't want to take it off if its serving another purpose.