The difficulty of earning credits in advance is very, very high, and there is a certain risk. If the credits are not enough, not only can they not graduate early, but they may even fail to complete their studies, which would be a waste of a college entrance exam.
Especially for a top university like this, it is already difficult enough to get in once, let alone take on a risky task like this. Not to mention students, even the staff of the Academic Affairs Office are not willing to do it, as it's extremely troublesome and requires additional modifications to the database. Unless the student can prove that they are truly outstanding and have the support of a teacher, no one would take this risk.
