What is the upper limit of total number of productive hours of human race

We may all agree that the quantity will scale with the human population. But is that linear scaling, what is the coefficient, does this coefficent vary when the population change?

The question has obsessed me for a long time. With the idea of modern era that ‘the more (time) human work, the less time wasted, and the better/richer human will become’, I wonder how many hours we actually work. For example, the more people an organization has, the more they need to communicate/test/manage, or the more music/art produced, the time people need to .. enjoy it! Thus, it seems to me that there will be a limit of how many hours per day can a average person can actually work. Yet, I need to define every term carefully.

Working hours - Productive hours: the time that product is produced, excluding the preparation time, planning, … e.g: ‘working time’ to produce a car is the time that components of car are produced and combined? do we count the time for logistics/distribution? No, because it does not directly produce the car. “Giá trị thặng dư” chỉ sinh ra ở thời điểm hàng hóa được tạo ra. Sản xuất mới là thứ tạo ra của cải.

Productive aspect: which produce what is essential for our life (it’s hard to tell but I define it as ‘w/o it, human will cease to exist’, e.g ‘food’, ‘culture’? (may be culture is for high society level), …). Cuz all the businesses is finally just to help money to trade for good. We may not need transportation, but we need food.

To be updated …

Finally, given the fact I prove here, I want to relate it to GDP, Gross Domestic Product. For me, GDP reflects the total ‘working time’ of the country While every country claims/aims to have positive economic growth, I think that at the convergence, GDP growth is mainly caused by inflation, which mean that there will be no actually GDP growth. We can imagine this case as when all people in the world already ‘maximized’ their working hour.