I recently started a day job where I'm expected to work a normal 8 hour workday. No one is holding me accountable that I stick to that so it seems the requirement is more of a formality, but that's besides the point.
As I've experienced trying to keep up this 8 hour work, I've come to realize that sticking to this old assembly line convention makes absolutely no sense for our field of work. On a good day I can work even 12h+, but usually my limit is somewhere around 4 and ½ hours. And after six hours I'm just burning myself out trying to force myself to focus. At 8 hours I can feel physical pain and it will take me whole evening to recover when I get off the clock.
It's silly how many companies are still sticking to this old rule. Nobody wins when employees are wasting their time being inefficient. If the 8 hours workday is actually enforced, employees will just come up with coping mechanisms against the stress the overly stretched workday is causing them and they will end up loosing motivation.
Conservative improvement would be working 6h * 5 + 4h on Saturday (remotely), which would make employees more efficient, mentally healthy and that's 6 hours less work time per week.