Robert Comsol wrote:
"Maybe the usual turboshaft route is undergoing maintainence and it had to take the long route round?"
is the kind of rationalization I'll do my best trying to avoid whereever possible.
You don't need a maintenance event to justify a turbolift cab detour. Normal, day-to-day crew activities pretty much dictate that you can't always take the most optimal route. The turbolift routing computer must have a predictive algorithm that attempts at all times to balance two objectives: minimize travel time, and minimize wait time.
As soon as I give my orders and my cab whooshes away, the lift computer starts doing three things: (1) managing my cab's route (which may change based on other cabs in motion) for safety and optimization; (2) removing the empty cab from my destination to make room for my arrival; and (3) dispatching a replacement cab to my departure point. So each turbolift ride involves not one but three
cab routes. This is happening simultaneously for multiple crew members, all over the ship, and many of their routes overlap and intersect.
I would think it a foregone conclusion that my wait time, travel time, and actual route taken will all vary for any given combination of departure and destination points, even if there was never a maintenance event. Thus we are not burdened by having to assume that the lights we see sliding past the cab window represent the optimal route.
(P.S. Don't forget that each hull will probably need one or more "cab depots" where several cabs can be tucked out of the way, facilitating both #2 and #3 above. Each such depot can probably just be a "spur shaft" where a few cabs can be lined up like unused boxcars. Hmm, I may actually have seen something like this on blueprints or a cutaway at some point in the last 40 years.)