Have you ever worked on one thing day and night for several weeks straight? Maybe 60 or 70 hours per week at work? Do you get more work done? I think for a time. But what happened after about a month? You don't have to tell me because the studies from way back in the '30s, '40s, and '50s showed us that you don't gain much by sustaining those kinds of hours, according to http://www.inc.com/jessica-stillman/why-working-more-than-40-hours-a-week-is-useless.html.
...By the 1960s, the benefits of the 40-hour week were accepted almost beyond question in corporate America. In 1962, the Chamber of Commerce even published a pamphlet extolling the productivity gains of reduced hours.'
What these studies showed, over and over, was that industrial workers have eight good, reliable hours a day in them. On average, you get no more widgets out of a 10-hour day than you do out of an eight-hour day.
However, studies also found that you can get a productivity boost with those kinds of hours for a short time, up to about a few weeks, to meet a deadline for example. I indeed found all of this to be true for myself, as I came to the end of 4 or 5 weeks of long hours in August. I was in the typical "burnt out" state, telling my wife bluntly, "I don't want to work on it today." Yet I did, but shortly after decided it would be more productive, and healthier, to revert back to something closer to 40.
Yet from the first day on my first software job, and actually long before that, ever since I was a teenager, I've found myself always working on, or wanting to work on, something. Get home from work in the evening, work on project x. On Saturday, spend some family time, knock out a couple things on the to-do list, then work on project x some more. Granted with a family full of kids it rarely passes 60 hrs total per week, full-time job and side projects combined. And I find it completely sustainable. How? Because it's not 60 hrs of the same thing. It is often 60 hrs of programming, so it is all the same in that sense, but different kinds of programming: different project, different code base, different goals, motivation. It works. In fact, I find that the two projects seem to feed off of each other's energy somehow, coming back to one refreshed from the other. It's a change of gears, some variety. You experience this too?
So in the midst of this critical time in the start-up (...which is all the time in a start-up), I still find it necessary to flip the burger -- do something different, be refreshed, accomplish something else in addition, though much less time spent on it. I'm often tempted to feel guilty about it. After all, overtime is often a start-up entrepreneur's 6-point deer head mounted on the wall. The mark of a real go-getter, it is often portrayed. Yes those periodic bursts of work are necessary. But not sustainable, or productive for the long-term. No need to feel guilty. Refresh. F5. An unflipped burger is just gross.