Physical areas vs power districts
The Port Bonifacio railroad is sectional. So power feeds need to go to each section.
The Port Bonifacio is an "exhibitor's layout", so the tracks are divided up into power districts with separate circuit breakers so that a short in one will not stop the trains running in another.
But I did not fall into the temptation of equating the two. If I did, a short in one section would stop trains orbiting on both the inner and outer mainlines, once they got to that section.
So this is the physical sectional plan:
(the staging is on the upper deck, in yellow. All other track is on the lower deck. Access liftup bridge at bottom left, TranzDeck elevator deck at right. Note the museum section is actually three physical units, denoted by the dotted lines: two sectional modules and the lift bridge. But it is wired as one.)
and this is the power district plan
No connection between the conceptual models. A short in a switching area or staging affects neither mainline. A short in one main does not affect the other. [at least in theory. I am using Tony's PSXs and I am experiencing interference with the Zephyr in all districts. Working on this]
More wires to each section, more wiring work.
Easier to isolate a problem.
Each wire can be used for train detection: a power district in a physical section is near enough (in my case) to a detection block for a simple detection system.