Working less seems like reasonable advice all around.
To be honest I rarely have more than 3-4 productive hours in a day, where I actually get hard stuff done. Sure on special days I can be productive 8+ hours; but those are rare.
For me the open question is if you decided up-front to only work 3–4 hours, would you be as productive as you are in those 3–4 hours out of an 8 hour day?
I suspect that if you can habituate yourself to a sustainable number of daily hours (eg., 3-4) where you always work, barring illness etc. Then I believe you'd have a net positive output for most professions, and most software engineering domains.
J. Blow has much to say against this, but i've never really heard him engage with this integral of productivity given habituation. I guess his reply to my argument above would be, "sure, but are you actually working these hours? if no, it's just rationalisation for lazyness"
I would have to try it but my feeling is I would be just as productive.
Of course this is related to creative work, like coding, writing, design etc.
Less creative work like kitchen work, or manual labour in general I can do until my body gives up (16h shifts used to be no problem but I'm getting older...)
Sometimes I can do weeks worth of work in just 30 minutes. Some people can cut a lot of labour time perhaps years worth for multiple people. Productivity can get hard to measure.
To be honest I rarely have more than 3-4 productive hours in a day, where I actually get hard stuff done. Sure on special days I can be productive 8+ hours; but those are rare.