Together with the Yin Linking Vessel, its counterpart on the body's inner aspect, the Yang Linking Vessel completes a division of labor distinct from the waking-sleeping split the Heel Vessel pair handles: where the Heel Vessels divide the body's rhythm in time, the Linking Vessels divide it in depth, the Yang vessel binding the exterior, surface-level yang channels and the Yin vessel binding the interior, deeper yin channels.
That surface-versus-depth distinction gives Chinese medical diagnosis a way to distinguish a genuinely external condition, chills and fever from a fresh pathogenic invasion still at the body's surface, from a condition that has already moved inward, a distinction with direct consequences for how a practitioner working in this system chooses to treat it.
The Classic of Difficulties states the pair's disorders in a single short passage, giving chills and fever to the yang vessel and pain around the heart to the yin one, and it adds a third condition for the case where the linking function fails altogether rather than one side being disturbed: the person is described as unsettled and without strength, unable to hold themselves together. That third case is the one that shows what the vessels are actually for, because it is not a symptom of surface or of depth but of the two ceasing to be coordinated.
Read that way the Linking Vessels are less a pair of channels than a statement about the body's coherence, which is a different kind of claim from anything the twelve regular channels make.