Cornell's One Course At A Time curriculum gives you as an international relations student, the opportunity to travel outside the U.S. on multiple, study-abroad opportunities. Shorter trips are more affordable. It's also much easier to fit study-abroad time into an academic plan that involves more than one major, since you don't need to be gone for a whole semester to take a trip.
Individual projects on campus are facilitated by the calendar, since it lets you focus intensely on a project without having to divide your attention amongst other classes.
Finally, you might have the opportunity to take a block off during your senior year to prepare for graduate school entrance exams, the foreign service exam, or job applications.