Yes, you're absolutely right. There's definitely a cost associated to part time workers. But that doesn't mean the current 40 or so hours a week (in Australia

Yes, you're absolutely right. There's definitely a cost associated to part time workers. But that doesn't mean the current 40 or so hours a week (in Australia it's 37.5) is the optimal amount of hours that a worker is productive. If the worker is actually working 20 to 25 of those hours and the rest is made up work then you're not really getting things done any faster. So I think your analysis rests on the assumption that every hour of those full time hours is actually a productive hour. I think anyone that has worked can probably vouch for the contrary. But I reckon there's a kind of "the emperor is naked and everyone can tell but says nothing" situation, where we want to pretend we are all much more efficient and productive than we actually are. Part of it probably comes from the need that everything needs to be sort of standardised otherwise it'll be too much overhead for management. So it's a very difficult problem, but I think smaller firms (20 to 100 people) should probably experiment much more. And they kind of are with 4 day weeks and so on.