/// No. The reason I was given, and have always believed, that the master cylinder needed pre-bleeding was that a dry master cylinder would have small bubbles adhere to surfaces inside the piston. These small bubbles might dislodge at random times. Usually they rise and self bleed into the reservoir. If they are in the output port they will be there a while.

Reguardless, until they dislodge and rise they provide air to soften the pedal. You cannot tell if the soft pedal is from those bubbles that will self bleed or bubbles in the remainder of the system that will not self bleed. The only answer is to eliminate all bubbles and deliver a hard pedal to the customer.

If your master cylinder was used/wet this will not happen. I always gravity bleed. None of my cars have ABS. I work alone. I use vinyl tubes and 20 ounce Pepsi bottles, holes drilled in the caps for the tubes. With this method and starting from an empty master cylinder you would not, repeat not, need to bleed the output ports on the master cylinder. That is done only when a new master cylinder is put on a full system.