In the marketing agency world 50-60 hour weeks are the norm and 70 hour weeks occur once a month or so. It isn’t really sustainable. Most people burn out and leave the agency world within three years. Those that stay often make work their life or have a way where they can set their own schedules, which is usually because they have reached marketing executive level and the work becomes different.

It is a very unhealthy industry. I am not sure if it can be sustained in it’s current form, but I don’t ever see the hours being reduced either. 4 day work weeks would just mean 12+ hour days and you would have to hope your clients aren’t open on Fridays or whatever day you decided to make your company day off. Staggering days wouldn’t work that well as most agencies have little to no redundancy by design.

How much of that is working time, and how much of it is sitting in a room not being productive? Every productivity study I've read finds that per-week productivity drops off tremendously with that level of overwork.

Productivity per hour drops, but it doesn't matter to the agency because all of their employees are salaried. It is not people sitting in a room not being productive per se, but it is a bunch of burned out employees not being as efficient as they could be.

Again, this leads to burnout and employees that are sufficiently burned out either quit or are fired for no longer being able to meet the productivity requirement and/or making mistakes. The agency does not care because the supply of recent college graduates in marketing and communications is never ending (it is one of the most popular majors at almost any college/university).

Interestingly, slower work to a point is better for the agency since they bill the client per hour. That reverses when the quality of work suffers or the employee is no longer able to get everything done that was promised to the client. The agency gets more value out of a single employee when they work longer hours. Bonuses are common in the agency world, but they are typically meager compared to the extra hours worked. Burning out their junior employees is then to the advantage of an agency that bills by the hour.

I can work 55 hours a week in perpetuity as a founder, with the exception of four off grid, week long vacations a year. Even two weeks over 60 hours (e.g. fundraising across timezones) and I rapidly lose it.

But is your overall productivity higher with 55 hours than it would be with less hours?

It's the kind of question where I wouldn't really believe your answer, unless you've actually tried to experiment yourself where is the cutoff (for your specific situation) between hours / productivity.

Not because I think you would answer in bad faith, but because it's a really complex question. What if working less hours over multiple years would let you pursue some hobby, turn you more sociable and thus a better leader/CEO?

Or maybe it would make you just very slightly better at decision making. You would have less time to manage your company, maybe relying more on others, but in exchange you would have more energy for the really crucial decisions. Or enough energy for extending that 2-weeks international crowdfunding effort into a 3-weeks.

Yes, over the course of a 12 year full time career, if I go above 55 it gets worse, but I can sustain 55. In terms of trade offs, there's something to be said for parkinson's law. If I have way more than 55 hours a week of stuff, I know I have to fit it into 55 or I'll burn out. If I aim for less, I find I never end up working less than 40, even if the absolute amount is much lower.