>>1613265first, some nomenclature clarification. there are three types of two-rope systems: twins, halves, and twin/half hybrid.
>twinsboth ropes have to be connected to every piece of protection
>halveseach piece of pro should only have 1 rope attached to it
>twin/halfone or both rope may be connected to each piece of pro. this is how most half ropes are rated.
as for the primary value, it's for reducing rope drag on wandering climbs. see pic related.
fwiw i have halves and a 70m single, and if i know i'm going to need to do full rope raps i'd rather just bring a tagline and save the extra weight and rope management of my halves.
finally do NOT use a rope rated only as a single in part of a two-rope lead system. if you fall it will halve the shock absorption, doubling the impact on your body, and possibly fucking you up.
