We aren't really disagreeing. Air in the lines will add more water than just the air at the top of the reservoir. Dealership mechanics make mistakes. For that reason, I avoid having a service done more often than it needs to be done. Every year or two for the Leaf, save maybe in a tropical climate, is more often than the flush needs to be done. This service interval was a sop to the dealers by Nissan, not dictated by the complexities of the braking system..
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.