A recent comment from reddit: This year I became a co-owner of the company that worked at for the past three years. It's a small development and consulting company and we're currently struggling to find new developers. At the same time, my girlfriend is trying to get her foot into this field. Since she's interested in a completely different tech stack than what we use, hiring her through good ol' nepotism is not goin…
This is crazy. If the junior needs more than 1 hour a day to be net positive (= do more work in the remaining 7 hours that you would do in that lost hour) then I would say they are a lost cause.
This is also so easy to filter at the interview level - give them homework to learn some new skill, junior candidates are generally willing to spend significant time on that and it gives you much better picture of their abilities than whiteboard puzzle.