I'm curious about the stats (if you have them): how many of the candidates added documentation ? because one could argue that documentation by itself is not DRY since now you have both the code and the description of the code (the docs). if the code changes - you MUST change the docs as well (otherwise the docs and the code are not overlapping, which is much worse than not having docs in the first place).

I might be completely wrong about documentation not being DRY, but this by itself could be a good conversation with a candidate .