Extended, multi-year pumping does contribute to permanent size increase as part of a long-term PE program that uses multiple modalities.
Short-term size increases dimish over time starting from the moment you pull that slab of manhood out of the tube to the time you catch yourself in the mirror and it's back to its little ole limp self! And all within a number of hours, or sometimes a day or more for the experienced pumpers. And to think that fleeting, wondrous enhancement, only depends on a few factors such as: duration of pump session, time in and out of pump, dry pump, water pump, using proper equipment, tube size, years of experience, your pump program or pattern, massage time, lubes used and so on and so on.
Not surprisingly, it is the short-term pumping experience and its "inability" to produce a long-term or permanent effect that brands Pumping as usless.
Well, all good things come to those who wait and, I might add, does due diligenge in following their PE and Pumping regimens.