Jacklines (vs jack's line)

[JohnV]

Brion, your point addresses my original question of one long line vs 2 short ones: which is more likely to fail when a weak point is stressed beyond its limit?

Here’s been my thinking—if you can bear with me:

One long line involves 3 hardware attachment points and 2 splices (given a round turn at the anchor bit).
Two short lines: same 3 hardware points plus 4 splices.
If those are the weak points, then one long jackline wins 7 to 5.

But, with a long line, unseen fatal damage somewhere along the rope—let’s say it's on the port side—can break whichever side you fell against. With 2 separate jacklines, you can fall safely on the starboard side of the boat, so your first fall has 50/50 odds. Fall twice though, it’s 3-to-1 you’ll break the rope. (2 falls can be P & P, P & S, S & P or S & S). Fall more than once or twice, or add more chafed spots, and you’re a goner with either jackline arrangement. (Might as well jump overboard before you break something.)

Intuitively, between the structural weak points and random chafe point(s), one long line seems less vulnerable to me. But that’s all hypothetical, and real-world experience with the issue carries a lot more weight. What do you think of my reasoning?

My thanks to all who have weighed in so far.
John V.