This finding suggests that not only do students underuse formal office hours, but that the very presence of such a schedule inhibits them from seeking out the instructor at other times as well. This finding has important implications for college-level instructors everywhere, depending on their goals. Instructors wishing to minimize contact with students should schedule formal office hours, whereas instructors wishing to maximize such contact should not hold formal office hours. —“Angry Professor” —Student Consumption of Faculty Effort in Formal and Informal Contexts (A Gentleman’s C: The World Needs Ditch-Diggers, Too)
This is, of course, satirical and exaggerated, and it’s written by a professor who teaches large classes at a large state institution.
I generally leave my door open because chatting with students is a great way to procrastinate.
I do have several stages of signaling “leave me alone.” I might just close the door; I might close the door and turn off my light (though I know the silhouette of me seated before the computer screen will be visible through the frosted glass); I might put a little sign that says “I’m Grading” on my door (with a smaller note noting that I will check my e-mail before going home for the day); or I might pack up and find a quiet corner of the library.