Seems like a really obnoxious way to communicate though. If they want somebody to do their best work and really do not care how much time it takes them to get there, they should just be upfront about it: "You have until next Monday, good luck".

If that makes them look like assholes, yeah, I can see why someone would feel that way but at least they are clear about their intentions and not insulting anyone's intelligence in the process.

Are they though? Playing Devil's Advocate, I have a pretty good idea of what I can do in 3-5 hours of solid work. If I was hiring for someone to replace me and asked the same question, I'm fairly sure I could tell whether it had been 3-5 hours or 3-5 days.

It'd be more useful to know they could execute roughly what I'd expect in 3-5 hours. As in they think quickly, come up with something, get the basics down and are ready to progress or not.

...Of course, if they're doing it at home they could spend 3-5 days on something I'd spend 3-5 hours on and I'd never know...