Some summer courses are contingent on enrollment and may be cancelled if enrollments are insufficient. You can check which courses are contingent on the number of registered students by reading the class notes.
Marquette's 400-plus summer options includes dozens of required core
classes, allowing you to knock out a few credits while still making the most
of the sunshine. Just think of it this way: The sooner you fulfill your core
requirements, the sooner you can get to the heart of your major.