alt Hacker NewsLook, if you want to make people do work samples from an uncomfortable conference room at your office, be my guest. I am pretty confident I speak for the majority of candidates when I say that that my preference would strongly be for the ability to work on this stuff from wherever I want to.
I mean, that doesn't have to be how it works. You can have a both fixed amount of time, and the ability for a candidate to work in whatever environment they want.