Fact is, I'm productive with a 8 hour a day schedule if and only if:

    1. What I need to do is clear and known.
    2. I've been doing the is same everytime or something of similar pattern.
    3. No meetings and distractions in between.

But the fact is, none of this is true in our area of work. To some extent even if something similar exists it wont work for many reasons.

For every person who wants to go back home, there is always a peer who is putting in extra hours innovating, building and learning. By the well known rate of success coming at an near exponential rate to people to work hard and are productive, the rate becomes exponential if they add crazy work hours to it.

Building stuff requires a goal. Then implementation, experimentation, test a feed back loop and then back to implementation. And then this cycle goes on in iteration.

This requires tuits(Uninterrupted large workable free chunks of time) to allow a degree of focus and flow seep into the person. And most of tuits are generally available only early in the morning or in the night. This by default means you already agree to work crazy hours.

So in summary, I can't do a 40 hour work week because

    1. I will loose out to my peers in the long term race.
    2. Meetings.
    3. My work requires genuine supply of atleast two big tuits a day to remain competitive and have a good growth both money and career wise.