Effective working hours are not set by absolute productivity - they are set by an equilibrium between two forces:

1. Competitive market dynamics. If you only work four days a week, other employees and companies who are willing to work five days a week will do so and get ahead of you, and you are more likely to get fired or to go out of business. This force pushes us all to work longer (and harder) so we have more money to enjoy in our leisure time.

2. A society's willingness to sacrifice days of leisure for days of work. There are only seven days in a week. The tradeoff between work and leisure - production and consumption - is ultimately what determines how hard we all work. This force pushes us all to work less so we have more time to spend our money.

Economists think on the margin. It's easy to demonstrate these two principles to yourself by thinking through worked examples from different starting points.

Whether the equilibrium lands at 2 days of work to 5 days of leisure, or 5 days of work to 2 days of leisure, depends on our collective preferences, which vary between countries and cultures but have tended to be relatively durable over time.

No technology so far has shifted this balance much - not the steam engine, the industrial revolution, the invention of the personal computer, the internet - and there's no reason to believe "AI" will be any different.

The logical conclusion of this is that - assuming we're all 10x more productive - we'll still be working 5 days and enjoying 2 days a week, but we'll consume 10x more, or everything we consume will be 10x higher quality. Hardly a bad thing.