This is not a true statement. I run both front and rear air lockers from the arb compressor. It runs for 7 seconds when I hit the switch and about 3 seconds when I turn both lockers on and off. In a whole day of wheeling, it might turn on by itself 2 or 3 times. It's usually running more because I leave them open unless I need the axles locked up, so I'm turning them on and off all the time.
Volume in a storage tank has nothing to do with pressure required to actuate the lockers.