Most people are just being annoying packing up early, but I tend to give the benefit of the doubt. Some people need that couple extra minutes. One semester, I had class in Kildee with choir following it down in Music Hall. You had to sign in for choir every day, and if you weren't there by the time they pulled the sign up sheets, (pretty much by 11:02), you were marked late. I think you got 2 or 3 lates (plus the look of death from the director) before it dropped you a grade. So yeah, I usually tried to quietly pack up a minute or two early.