@Marian Some colleges make it almost impossible to change roommates. It has nothing to do with the “work,” but rather that they have decided in a very nannyish way that students should be forced to work out their differences, regardless of how miserable they are.
Some colleges don’t even allow students to select their own roommate, at least for their freshman year. A few of these are elite schools that can have any rules they want. Otherwise, I would discourage my children from attending a school that didn’t allow roommate selection.