Why do you want to work such long days when there is so much evidence that total productive work per week doesn't increase beyond around 40 hours of work for most knowledge worker jobs, especially software development?
You're right to bring this up, and certainly those studies are the best hard numbers we have, but:
Do the studies correct for employee satisfaction with working more, corporate culture, employee skill, employee personal life status, or level of excitement/interest in work? Because I think all of those would be a positive factor at Apple.
I find that I have significantly more than 40 hours of usefulness in any given week. I almost never work 9-5 M-F. I usually show up later, and stay later; in my experience, I feel most awake later in the day and do my best work later as well. Occasionally, if I'm working on a problem, I can get a lot more (efficient) work done keeping at it rather than leaving and having to spin up again on it.
At other times, of course, leaving is the only way to clear my head and find a solution. It all really depends on your working habits; mine just don't tend to be very consistent. :)
How about for a fixed time period, like 6 months, I remember something being posted talking about long term longer hours but I think there is more to look at here.
For instance what if I work 8 hours a day usually but a couple of times a week when I am in the zone put in 12 hours? What if I make up an extra 4 hours casually on the weekends? It'd be hard to say that there is no way to include more than 40 productive hours into a week, using any scheme.
Why do you want to work such long days when there is so much evidence that total productive work per week doesn't increase beyond around 40 hours of work for most knowledge worker jobs, especially software development?