Whilst I'd love to have them do a paid project for me that will actually ship, I work in a part of the programming world where a project easily runs a decade from first draft of requirements to entering maintenance. This sort of suggestion always seems to come from the world of web apps or SaaS or whatever else is hip at the moment.

I also can't imagine what HR would say if I told them I wanted to hire someone for a week just to see how they get on. "Well, then your HR system is broken and you should totally hack it to make it better." I'll get right on that, just as soon as I become Vice-President of HR. They'd tell me to do my job and hire people who can do what they're hired for.

Where this is going is the ripost that this kind of suggestion always comes from the small part of the industry where it might be practical; the are are a great many programming jobs in companies where it really, really isn't.