study for every hour of class to get an A and that was assuming you were a great student. Some it will take less, others a lot more. I had classes that took nothing and others that too 6-7 hours for every hour in class. It isn't for the students to judge how hard a class is.
I had a great professor at BYU that never in his 30 years ever gave an A, but if you got A-s, he would go out of his way to help you get into grad school. Poor guy died a very miserable death from MS>