You CAN take a 40hr week worker, make them work extra, and their productivity will spike pretty hard. It's just that people eventually adapt by resting more at work. Employers end up seeing little additional work done even if they schedule somebody for an extra 20hrs a week.
The only jobs where more hours = more work sustainably are jobs like trucking where the work is actually very easy and its just a matter of staying awake at the wheel. Long work weeks are mostly a form of virtue signalling which you recieve money for doing. The only reason the 24/7 crunch time companies don't immediately go broke from sheer inefficiency is because they don't pay their staff overtime. Everybody would be better off in the long run with a culture that was focused on hiring a greater number of people to work more reasonable hours with strongly encouraged breaks. This 996 crap is a reflection of the egos of people like Jack Ma who would rather have employees with his work ethic rather than employees that get a lot of work done in little time.
I think you also have to figure in the absurdly high value of the sort of work we're talking about. A company can launch a website after investing $2 million in its creation and have it pay for itself in a few days. That sort of return on investment is big enough to cover a multitude of grave sins of inefficiency. That's why companies can persist with open floor plan offices which over 1000 studies have shown destroy productivity, having high attrition on purpose so they can staff primarily with entry level candidates, and renting expensive office space that actually drains value rather than contributing any.
Yet for the companies involved this arrangement is highly profitable. They don't pay any of the externalities. I'm not saying it's a good thing. It's merely a profitable thing.
My coworkers were no more productive than me: IMNSHO, they would end up dragging as much busywork out of every problem as they could, simply because they were too overworked to think more than one step ahead.
To wit: we were running 10 AWS servers - to serve a mostly static website and handle a few hundred REST API calls each day.
Of course, if the client actually has to pay $200 per hour you're present, it's exceedingly likely that the overtime culture will stop overnight. It's obvious that it isn't working already, once the company actually pays for it as well, it is bound to stop.
The problem wasn't the long hours - it was that places that push long hours tend to get other, even more important things wrong as well, like product-market fit.
You could do taht with 2 instances and dropwizard (https://www.dropwizard.io/1.3.9/docs/)