I think it depends on incentives. Are you properly incentivized to work that hard? Also - do you believe in the vision of the product? The answer should be yes

I think it depends on incentives. Are you properly incentivized to work that hard? Also - do you believe in the vision of the product? The answer should be yes to both to warrant that kind of commitment. Even a lot of equity or cash cannot sustain hard work if you don't believe in the product. Additionally, this type of time spent can only be done on short time periods and you need to see success at each milestone to warrant ongoing work. So is the big picture vision broken down into reasonable success milestones? Finally, your physical and mental health is paramount. Working that hard will take a toll on both if you dont have a balance. 7 days of work per week is feasible if you can take some time to exercise or relax within each day. Your mileage (MPG) can increase if you go slower, even if you are working everyday - and will take you further on the long stretches. Its a balance...