My concern would not necessarily be that some candidates will gild the lily, but that you will get poor performers taking an entire week to turn out a reasonable “four hour effort”. Some people simply work too slowly to be productive.
I’m also not sure you don’t introduce hidden biases. I don’t comment throwaway code. For that matter, I comment production code very sparingly. Will I be penalized for not including a full docbook manual with my code? If you ask me about comments, I can explain my preference, or even explain that I’m happy to write as many comments as local standards dictate, but that’s not something you’ll see in a fake work sample.
Exactly. A few jobs ago we gave a take-home problem, and it was timed – you get the problem, do it right away, turn in your solution. We told them we expected it to take at most 3 hours. Even then there were people that thought they’d please us by turning in a solution 8 to 24 hours late. I can guarantee that if you give a week, there’s people that will take the whole week. And then you bring them for an in-person, they fail, and you just wasted a week of their time.