First, thanks for the thorough response! I totally agree that link building is about building relationships. I would have to disagree however, that if we shoot for 10 sites a day, the answer will always be 0. I was in no way implying that we just send generic emails asking for a link and that's it. Let's take blogs for example. If I had a dedicated resource spending all day reading industry blogs, contributing, etc...wouldn't you say that 1 hour reading through 1 blog is sufficient to understand that blog in such a way that you can formulate an email that can demonstrate your knowledge and start a relationship? If this resource works 8 hours a day, that's a potential 8 new relationships. Maybe I'm naive, but with the time and effort, I think it's possible.
