Back when I was in my 20 and, after many dates leading up to, finally made love to a certain beautiful girl friend, I came three times without us separating. The first one was as I entered, I was so excited, but she didn't realize, and I vowed to pretend it didn't happen and soldiered on. In very little time I was as hard as before and we had a prolonged session. When I came again, I was surprised to find that I was still able to continue and we went for a lot longer until I came the third time (she thought it was the second). I have never duplicated that feat. I was unusually inspired, she was gorgeous and possibly my future bride (we eventually parted ways over Frank Zappa and all that implies.)
Fairly recently, after I entered the hobby, I became aware of the "cum after the cum" which I have described in a few of my reviews. Basically, after I cum, if my partner doesn't stop doing what she's doing, I go into a post-cum orgasm that is far more intense the the initial cum. It can last for several minutes and it's amazingly intense. Probably a lot of guys would be over-sensitive and this would hurt, but lucky me.
I noticed in a porn promo that this happens to Peter North. The scene: in an ad for a website, he is being blown by a pretty girl who is also talking to you about the website. She brings him to ejaculation, then looks back at the camera and tells you to go the the website being advertised. She is not paying attention to the fact that she is continuing to stroke him as she talks to you. After delivering her lines she looks back and sees Peter twitching like a fish out of water as she pumps him, and she is genuinely surprised to see him twitching like that.
I have danced on the edge a few times, withholding completion, but it takes concentration and it is more like sex for sport rather than loving-joining.
Alas this is mostly moot for me now at almost 70. I'm lucky if I can cum even once.