From what I’ve seen over the last few years, productivity works a bit like income/debt. You have a ‘set point’ per day (e.g. 7 hours of solid work). You can force yourself to go over this (e.g. an all nighter) but there are consequences next morning.. (if there are increasing returns to one block of time vs. splitting work over two days then doing the odd all nighter makes total sense, you end up net ahead.)
If you keep going over the set point, your need for rest gets ever greater and you keep feeling tired. If you ignore this and keep pushing through, you get burnout or your per-hour output just falls due to procrastination.
Implications – there are two paths of attack if you’re trying to maximize output:
1) Get more efficient (do the right/most important things only, stop wasting time reading pointless things)
2) Raise your productivity set point
Since ‘choice of thing’ follows a power law (the most important thing are usually way more important than item #6 on your todo list), it follows that #1 is the more impactful one in ROI terms. i.e. benefits of +10% efficiency divided by effort required to do so is greater than benefits of +1 hour of work a day divided by effort required to do this. That said, worth doing both in parallel.
I believe it’s generally worth working at the max set point if you really care about your work. Moreover, most people’s set point is higher than the typical working day (9-6 or whatever), so in practice you can be a ‘sustainable workaholic’ by just working at/near your set point. For me this seems to be roughly a 13 hour workday (9am – 10pm). I can do longer ones, and have worked 24-26 hours at a stretch, but I couldn’t do this repeatably over time.
Some people seem to have abnormally high set points. I don’t know how to increase your set point over time, but some hypotheses:
1) Progressive overload, same as weight training.
2) A healthy amount of delusion? maybe i haven’t tried this hard enough?
3) Your body can maintain higher set points for periods of time – based on passion for the project, or stress/adrenalin levels – however, not sustainable
Incidentally, sleep follows a very similar model.