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Here is some more guidance that we do not practice on our system. You should put the documentation right into the code. I am not sure if that is the same as saying your source code is the documentation, or whether you should add a lot of comments.
Do you want high developer productivity? Then focus on quality. In fact, quality is the single biggest factor which determines whether the team shall succeed.
P.S. Do nightly builds. It will increase your quality.