From the emlid Navio2 docs/Hardware setup:
In case of power module failure Navio2 will switch to power from the servo rail.
Powering servo rail
Power module does not power servos. To provide power to the servo rail plug your drone’s BEC into any free channel on the servo rail. Use BECs that provide voltage in a range of 4.8-5.3V. If you’d like to use high voltage servos use a power separation board.
ESCs are connected to RC outputs labeled from 1 to 14 on a 2.54mm header.
Only one ESC power wire (central) should be connected to Navio2 servo rail, otherwise BECs built in ESCs will heat each other.
In the ‘Wiring the ESC PWM Lines to Flight Controller’ lesson of the ‘How to Build a Raspberry PI Drone’ there is no mention of having only one ESC power wire connected to the Navio2 servo rail. So, I am confused as to whether or not I should cut the ESC power wire from three of the ESCs connected to the servo rail, leaving only one ESC with a power wire per the Navio2 docs.