I never visited my professors or TAs during office hours. In retrospect, I see I missed free one-on-ones, not only to ask about assignments or tests, but also to talk about the big pictures, misunderstandings, etc, etc.
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Our alumni network sends out a quarterly academic publication, and it's always nice to see how certain former peers/instructors "panned out" — e.g. a former classmate is now a nobel laureate (mutually-unknown, but I supported his team's hardware as a student job). My favorite are former TAs from my introductory labs that are now running their own quirky laboratories (many of us smoked.erryday.homies, at least at the time..).
It was only a decade after grad school that I realized how important people / networking can be. I am not a typical graduate, but "go Dores."