And yeah the wires are appear longer and more splices but how does that increase the load? More current in them because of the added length and splices?
Dave pretty much covered it.
Lets be sure you got it.
Go back to my mark up of MAD's diagram 'B'.
Trace your finger over the purple arrows from the alternator to the main junction.
How many connections?
Did the wire size drop from 12 gage or 10 gage to a smaller wires along the way?