Will pump 50 strokes, then take a break (usually get a cup of coffee). From then on, it's a shorter break every 25 or 30 strokes. Does take a bit of time to fill some of the large volume guns/HPA tanks, but for a Disco will usually get it done quickly with just one cooling break (pumping from 1000 to 2000PSI takes about 50-60 pumps).
Haven't owned all the pumps, but have owned 4. IF they work right from the start and you keep them from over heating as described above, they seem to last for years. A bad one will usually show it's fault within the first dozen fills.
Would be that 90% of the dead pumps are killed by over heating. That little final o-ring is small, and the focus of all the pressure/heat generated....they cook.