We love talking about productivity here. You're telling me employers will systematically fail the candidates who performed most productively in their process, because of a speculation they took too much time?
Any candidate capable of actually inventing a time machine should certainly be hired.
Also, such a system does not prevent cheating, which is really the worst issue here.
No candidate wants to be entered in the Hunger Games for who has the most time to sink into a take-home.
I don't want an architecture astronaut who is never going to ship anything.
An 80% solution when I need it is infinitely more useful than a 100% solution that's months late.
I need a stable system that can tolerate the real world and handle messy inputs without shitting the bed. A new hire that shows they consider their inputs and handle edge cases is a better fit to me than someone who focused on that 80% solution and didn't bother sanitizing inputs and crashes because of it.
Limits are fine if you ask me. Give me a couple days in which I can do this on my own time and if my kid needs me for something 10 minutes after I started I can deal with it and just come back to the test an hour later. Specific hours? Screw you, not even gonna start.