Forget about the social expectation for a bit - I don't think it's a good idea in terms of attracting the best talent that you can get. There are people who hav

Forget about the social expectation for a bit - I don't think it's a good idea in terms of attracting the best talent that you can get. There are people who have better things to do with their time than spend an hour or more on a programming puzzle for a company they've never talked to. You want to hire these people. In terms of economic efficiency, it's much better overall to do resume-screening before the coding challenge. Both you and the candidate spend something less than 5 minutes each checking if it might be a good fit before committing to spending much more time on the process. With the challenge that early, you either make people waste time when you could have found out more cheaply, or you convince people that it's too expensive to find out more about your compatibility.