Well, a 50′ length of line is OK.
Repairs: I broke a hiking staff several years ago, a splint and wrapped with line. Patched up my canoe seat. Repaired my waste belt. Cloths line/net hanging under my tarp. Replacement shoe laces. And so on. Usually, the main body is cut into one 25′ section and three 8′ sections. Then loops are added at each end. You loose a little for the loops. If I need the full length, I just loop-to-loop them together. ‘Corse, I am usually out for 1-2 weeks at a time. I need some sort of repair gear. I usually start the spring with 50′ or so, by fall it is down to 16′-20′ or so. For a quick weekend, you can probably do without, though.
For a ridge line on a tarp, I find that 30’ works pretty well. If I need more, I simply add the appropriate piece. Mostly, I do not use a ridge line, technically speaking. However, a cloths line works well to hang my cloths at night. Worst case, It gets them off the ground. Sometimes they even dry.
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