Explain: Pump less = more milk?

DottyBlue

Over the past week I have seen several references on this board and others to spreading out pumping sessions in order to express more milk.  (read on, this isn't as obvious as it seems) 

The implication has been that some women, if they were to pump 2x in 4 hours would get 3 oz each session (6 oz total) but that if they pump only 1x in that 4 hour stretch they get 7 oz.

How is this possible?  Same amount of time, same pumping time and conditions, but your body produces a full oz of more milk?  Has anyone really experienced this?