I'll agree that its not about how long you work, but how productive you are while you are working. While there is no substitute for genuine, hard work, I'd advocate that a polyphasic sleep schedule can help some people with long hours of intense work.
I disagree. Naps are inefficient. By breaking sleep up into more blocks you multiply the time you waste trying to fall asleep, shaking off "just woke up" grogginess, changing clothing, getting to and from bed, etc. Batching tasks is almost always more efficient. Grocery shopping every few weeks is much more efficient than going twice a week, for example.
I did some shift work for a while so I speak from experience. I would get about five hours of sleep before waking at 4:15am, and then take another hour or two of sleep in mid afternoon when I got home. I adapted comfortably to this and didn't mind it too much. But it did absolutely nothing for productivity or alertness. All it meant was more time spent changing in and out of PJs and lying in bed falling asleep. It also constrained the flexibility of my schedule because skipping the nap did a number on me.
Are people in siesta countries notably more productive than regular night sleep countries? I think evidence indicates the opposite. This whole "hacking sleep" thing is a red herring.