can anyone speak to the link between coherence and tree traversal?

the article and paper both seem to assume this connection should be known to the reader while also suggesting this paper's discovered methods could answer the relation, could someone bring me up to speed?

    “
    It was assumed the energy gets to the reaction centre
    in a random fashion, like a drunk staggering home.
    But quantum coherence would allow the energy to test
    every possible pathway simultaneously before
    travelling via the quickest route.
    ”

how complex are these routes? the paper cites that the team was able to use 'Crystallographic analyses [to] reveal two very different quaternary structures' but i was unable to find any information on the complexity of these structures

Traveling salesman problems can quickly become unwieldy so even if you allow for the route traveled to be thought to be the quickest, testing this hypothesis is equally intractable with current mathematics

from the paper:

    "from the insertion of a single amino acid, 
    the two αβ monomers are rotated by ∼73° to an 
    “open” configuration in contrast to the “closed”
    configuration of other cryptophyte PBP"

    "A central biological question is whether the
    presence of long-lived electronic coherence in the 
    light-harvesting proteins results in a selective 
    advantage for the algae—for example, is coherence 
    important for efficient light harvesting? If the 
    emergence of long-lived electronic coherence gives 
    cryptophytes containing the closed-form PBP a 
    selective advantage over the ancestral cyanobacteria 
    and red algae, it would seem that the Hemiselmis 
    cryptophytes, with their open-form PBPs, have lost 
    this advantage."

to summarise the paper would one say that the discovery of a new 'open' configuration in a light harvesting algae has given us a mechanism to, in the future, test the relevance of coherence to efficient routing?