I just came back from a trip, using two lines on prussics off each end, like Rip. I will never do it again. The prussics are a HUUUGEEE pain to adjust under tension. My fingers are raw and cut to hell from trying to slide the prussics for adjustment. This was using 1.75mm zing it. I will forever now use a continuous ridgeline (2.2mm also). Just like the one sold at whoopieslings.com.
I will also never use prussics on the corner tie outs. They were equally troublesome. I find Brandon's (warbonnet guy) method of self tightening stake knot to work best, and saves your fingers.
I literally have a half-inch piece of flesh missing from my pinky from fooling with those prussics this weekend. I immediately cut them off when I started packing up.