Students at many American colleges believe they may leave if the professor is more than 15 minutes late. In 2015 Michigan State University’s student paper reported that the university has no such guidelines. The University of Pittsburgh’s student paper reported the same.
At Cal State Fullerton in 2012, the chair of the Academic Senate described an older custom. Students had to wait a set time for a late professor, and the time was “dependent upon the rank of the professor.”