This is completely unrealistic - you clearly have never worked in food service or any sort of low wage customer facing role. There is a rush for each of the 3 meals of the day, and in between your volume is pretty low. And you never work a 10 hour shift, if anything they don't give you enough hours and you work 3-4 hour shifts.
> Then the receptionist can also work four days a week, with someone else filling in, rather than only those less visible
The difference is that the clever people who get their work done in 32 hours are still giving 100% output. The receptionist obviously cannot give 100% output if they are only present for 80% time.
> He reasoned that giving workers two days off instead of just one would enable him to push them harder, and get just as much work done while making happier employees, more loyal to him
No, it was not because they got just as much work done, but because it would reduce turnover [1]. It was a calculated economic decision. And in the real world, corporations have done that analysis and either decided on Ford's approach (as Costco has) or on the minimum pay possible approach (like Walmart). As a worker, you have the choice of going to Costco or Walmart to work.
I'll remind you that factory jobs needed a lot more training than fast food, which meant turnover cost had a real impact for Ford.
> But most businesses in which physical presence for given hours is important already have flexible scheduling to handle days of the week and times of the day at which business is busier.
But each worker still serves X customers per hour and works Y hours per week with flexible scheduling. If you suddenly have 20% fewer hours, then the worker has to get paid 20% less, else the business now pays more for labor. Considering a lot of restaurants operate on razor thin margins, this doesn't work out as well as you think.