>> A standard interview loop kills an entire work day, and is preceded by phone interviews that eat several hours. Properly budgeted work samples are strictly better from the candidate's time perspective, not to mention that you can do them from your couch rather than under flourescent lights in a confeence room.

Yes, standard interview loops also discriminate, and the more time they take, the more discriminatory they are. Any on-site requirements compound the issues.

Like Yegge says: provisional employment/internships solve all of these issues. You get the best of all worlds: stable employment for the candidate where they get paid a regular wage and aren't under a stressful interview setting, and lots and lots of work samples for you, the employer. It's not perfect. For example, it can be difficult to entrust the provisional employee/intern with anything impactful if you don't know whether they'll be employed at the end. But it is significantly better than the alternatives in most contexts.