... is a lot like Tim Gunn...of project runway.
Tim's stated goal is to give direct, honest and respectful feedback.
Wrapped up in that is taking the one-on-one relationship seriously and treating your grad students like young colleagues.
I've had friends who haven't been as lucky as me (A, in particular) -- as a result, I came to appreciate Dr. Advisor.
I'm sure Dr. A would have liked to get it finished more quickly -- but he also understood the demands on my time and he never set hard deadlines for me. I suppose I helped the situation by setting my own deadlines and generally meeting them.
Dr. A read and considered what I wrote. He politely disagreed with me and he realized that the dissertation is my project, not his. He told me early on that the point wasn't to write down what he thought -- rather, the point was for me to figure out what I thought and how it could be justified.
Dr. A also was willing to work outside his regular comfort zone -- because that's what I wanted to do. The fact of the matter is that the number of people in the country who could have supervised my dissertation is pretty low -- so, he told me that if it was going to get done, I was going to have to figure out the state of the field -- and he'd catch up. I hope that supervising my dissertation expanded his philosophical horizons a bit, even though I don't have any illusion that he'd have done that expansion on his own :).
The chances that I'll supervise grad students are quite slim -- but, I can take Dr. A's example and apply it to my own student and mentoring relationships. For that, I and my students owe Dr. A a large bunch of gratitude.