Good question, Jim. For years I had a similar view and was always in a bit of disbelief when others mentioned multiple pops. However, I think a lot of that had to do with the girls I was sleeping with. Just like you, I would have a long build up and a big pop, followed by some cuddling and be done. Not to brag, but during that build up (or before), I worked really hard on pleasing the woman and did my damnest to get her off first. Thus when I finished, we were both good and tired and completely spent. Most of the ladies I was with from here were satisfied and didn't really initiate any further intimacy (yes, you could also make the case that they weren't satisfied at all and didn't want to bother trying again, but let's not get mean - also, there were girls I was in relationships with and were sticking around for something). So without any further "prompting" from the woman, I figured we were done.
That all changed when I met a wonderful dancer in Korea. Very stunning girl who really liked sex and was always eager for more. So shortly after we finished the first time, she started to work my member again and surprisingly it responded very positively. Then after round two and a short break to replenish fluids, she started again and I was shocked that I was good to go. In fact, we ended up spending about 14 hours in bed and I probably popped 7-8 times.
Bottom line is that what I was missing before was a partner who seemed wanting to go again and was willing to "start my motor" again (such are young and inexperienced girls). The nice thing about being with a pro for a set time (90 minutes seems to be the minimum time required for multiple pops), is that after a short rest, there's not much else to do with your remaining time, so they will usually "get to work".