Transfer credits are applicable if the student is able to pass a validation test for the class at the academy. Regardless of how much time you spend at another college, you will still have to complete four years at the academy independent of what you did before or where you went. A 4.0 third-year student at Harvard will still start at the same place as a freshly-graduated high-school student. Even the service academies own prep school students (USAFA, USNA, USMA) do not get time credit.