I know this is late, but a lot of us really want to hire people, but there are a lot of people out there that are overconfident in their skillset, and sometimes you have to do a quick sanity check to weed them out. I agree, though, that most you can tell before that point. I'd never make someone donate a day to a test, but 15 mins of whiteboarding can go a long way if someone doesnt have a lot of publically available code to go look at (and, a lot of devs don't, due to working on public repos)