Speaking as an older guy, I think what you call "Superman" is no big deal. My pet theory is to be superman you need only 2 things:
(1) all your organs working well, especially heart and circulation, and all the plumbing, obviously
(2) having the nerves on your penis worn out and dulled due to usage, using my own experience I'd say... 10,000 ejaculation
So for part (1), yeah young boys have a big advantage. A lot of guys my age (I think) can't get erection all the time, because of heart and prostate problems, mostly. Also blood pressure and diabetes.
But for part (2), young guys don't stand a chance. Your nerves are hair trigger. Some guys even ejaculate during sleep (wet dream). Like a major part of kung fu training is destroying the nerves in your knuckles and other weak points on your body so you can punch and be punched without pain. To become a fucking superman you have to wear out the nerve endings to make your penis insensitive. Also, not just that young guys ejaculate very easily, the ejaculation is so intense it basically fry all the circuits immediately.
In ancient China, emperors and rich nobles go to ridiculous lengths to help their sexual problems in old age. Now I understand a lot of it is just heart/blood pressure problems. But another problem is that (for those who still have their organs in good shape in old age) they can not get orgasm easily. They can get hard, they can fuck for some time (depending on heart, lungs, muscle joints...), and their women can fuck suck whatever, and the dude just won't get orgasm.
I had the same for a while, I was pretty worried my dick isn't working any more, or overuse have ended my sex life prematurely. Then I figure it out and learned to enjoy it. Basically I have to really focus my mind to make orgasm happens. Sometimes I don't have the mental and/or physical energy to reach ejaculation and just leave it. Either solo or with a partner, I could start, not get to the end, and fall asleep with still a good erection. Usually can finish it next morning. If the condition is right (mainly free time and privacy) I can literally fuck all day, ejaculating once, three times, four times is no big deal.
But unlike the superman in the top post, I do sex/masturbation for pleasure, not for money. So I don't push myself to the limit. I think, just picking the little bits of gossips here and there and combine with medical knowledge and my own experience. There is nothing mysterious to male porn stars. They just fuck/masturbate a lot, to the point their cock is basically numb to normal stimulation. Then they can (1) get erect on command, (2) hold off ejaculation for as long as needed, (3) ejaculate on command, (4) keep hard or get hard again after ejaculation, (5) have more than 4 ejaculations per day. Years ago I heard some pros can have 10 ejaculations a day (making 2-3 different full length porn films a day), and I thought it's total bullshit, surely that's deadly. But now I think it's very possible for any healthy man, if he trains for it. Put it this way, I believe it's easier to train oneself to be like that, than to run a marathon.
No, I'm not saying I can do what male porn stars do, e.g. the most times I've ejaculated in any 48 hours period is 4 times. I have done 4 shots a day a few times, but I always give the little bro a rest for at least a day. Not that I have to, but I just don't want to push myself. It's not like I'm getting paid for it, right?
The point is, any man (I think) can train themselves to do 4+ shots a day all year round. But would you want to? It sounds good on paper, it looks amazing on AV, but does it feel good, is it fun? I really doubt it.
