I don't love that approach. There are lots of people who can do the work well in a reasonable amount of time but don't test well under intense time pressure.

I don't love that approach. There are lots of people who can do the work well in a reasonable amount of time but don't test well under intense time pressure. We do require candidates to use version control and (though we don't tell them so) we review individual commits to understand the candidate's approach and how they use version control, and commit timestamps to see how long implementation took them. And the volume of candidates who pass both resume review and phone screen in our process is low enough that we're not usually comparing candidates to one another; it's "can you do the job or not". So relative advantages aren't such a big deal.