Earlier quoted context omitted.
The original claim was about knowledge workers. In repetitive work of course more time is always gonna be more productive, with diminishing returns. Until the worker/slave mind or body breaks at least. Mind you, I'm not saying the same doesn't apply for knowledge workers. Just that this specific articles doesn't provide evidence for knowledge workers. I imagine that there will be more science being done for productiv…
My original claim was that there’s no research showing negative productivity for any job for less than 60 hours a week of work. If you have anything to the contrary please share. There is no reason to believe knowledge workers are any different than manual workers here. Your productivity turns negative when you make so many mistakes that you’re destroying value, not creating it. The article may be only weak evidence…
One thing to consider about knowledge/skill workers vs unskilled labor is that most complex systems are house of cards style situations where a single mistake can both destroy a network effect of value, but also take several orders of magnitude of time and effort to detect and rectify the actual issue.
Introducing a subtle, but value destroying, bug into a system can do value damage to the N systems it interconnects with, and can lead to a near total loss of the whole system (eg: drop table). Of course there are safeguards that can help avoid this like backups, but still the point is a carpenter wouldn't make the whole house worthless by a misplaced nail.