Now, the same cant be said about writing TPS reports.
A few nights ago,I got jazzed-up on the Vietnamese Iced Coffee I'd had with dinner, and I literally coded all night and into the daylight. I probably started around 8PM and ended around 9AM, working on my hobby project.
And honestly, if I hadn't been jazzed up, I would have stopped somewhere around 1:30AM, to my own great benefit. By the end I was spending half my available effort just staying awake and remembering how my code is broadly structured.
If I'd had to do something other than cycle through compile-run-debug, I would have failed completely. No matter your caffeine or passion levels, at some point you lose sanity points and Cthulhu arises from the depths to eat your code and then your soul.
Now, imagine the same hours on someone else's tasks and according to an inflexible schedule. Would it be the same? I think not. I imagine that is what you meant by 'grinding'.
So bottom line is that it's futile for management to push people that hard. Some people love the problem and they'll put tremendous hours int oit. But you can't force that upon anyone.
On the other hand, perversely, I can see the logic to it. There are 20% of people who are running full stream and being super productive for 14 hours a day. Maybe you just keep everybody in the office so that those people feel like everyone is making a sacrifice too? If you don't care about burning people out, I guess it is rational to keep people in the office if only 20% of people get more work done, if those 20% would leave if everyone wasn't there.