Ditto here - I did an interview with AirBnb once where I had 3 hours to build a mobile app from the ground up to a specification. They provided all the designs and assets necessary, as well as the API and specification. The exercise was broad, covered multiple areas, and was holistic (you get a shipping app out the other end, not an isolated non-contextual piece of code).

I rather enjoyed it, and at 3 hours wasn't a huge intrusion on my time. This sounds a hell of a lot more attractive than throwing a whole week of my spare time at a company I'm not sold on, and IMO is just as representative.

The extra perk of this approach is also that, assuming you give the same/similar assignment to every candidate, it makes their performance directly comparable.