That's true in the sort of desk jobs most of the people who inhabit Hacker News do. It's patently not true of things like manufacturing line work, delivery drivers, chefs, and call centre operators. A chef can't drop 8 hours a week and still expect to serve the same number of meals because of efficiency gains, and a call centre needs to be accessible at the times people are calling.

For the record I fully support any push to reduce the amount of work people are expected to do, but claiming there's no impact because of productivity gains just doesn't add up in many cases.

Actually, this is largely true even for other professions. A chef for example will slow down significantly after 5 hours of work and make more mistakes, so will manufacturing line workers and call center operators.

For sure, some jobs are more affected than others. But there are few jobs that aren't affected at all, and we shouldn't cut off the nose to spite the face.

> That's true in the sort of desk jobs most of the people who inhabit Hacker News do. It's patently not true of things like manufacturing line work, delivery drivers, chefs, and call centre operators.

The study wasn't restricted to desk jobs. Broader studies and international comparisons lead to a similar though weaker conclusion; in general more working hours over the range seen in most of the world (from about the mid-20s average hours worked per week, including both full workweek length and time off up) leads to a dramatic fall off in per-hour productivity.

> A chef can't drop 8 hours a week and still expect to serve the same number of meals because of efficiency gains...

Maybe, maybe not. Perhaps being better rested makes them collaborate better with the other chefs. Maybe the improved morale helps come up with a new menu item, or a more efficient way to make a dish. Maybe they wind up staving off carpal tunnel.

If the task is coverage-related (“be available to run a cash register” or “answer any phone call that comes in” or “watch this area for security purposes”), it’s exactly that ratio.

> If the task is coverage-related (“be available to run a cash register” or “answer any phone call that comes in” or “watch this area for security purposes”), it’s exactly that ratio.

But no task that actually needs done is purely coverage related. If you want someone to watch dor security purposes, you want them to actually effectively secure it to some level, and if average ability to do that drops from overwork you need more people; if you want someone to run a cash register, just having a body next to it isn't enough, they have to actually perform correctly.

Many coverage-related jobs don't require a person's full potential productivity, so the fact that their productivity goes down with hours worked is irrelevant. If a cashier at a low-volume store only rings up a customer every 10 minutes but you've decided that they need to stay parked by the register all day rather than doing other tasks between customers, it doesn't matter if it takes them twice as long to ring up a customer at the end of their shift as at the start.