Having taught undergraduate physics (at one of the ivy leagues), that echos my experience. The math and memorization are quite simple. But, it is the exposure to the concepts that takes time and seeing them a year or two prior makes a big difference.<p>I ended up socializing a bit with the students during optional study sessions and it was usually the people that came from more disadvantaged schools that needed to be there in order to keep up with the class. Some of them also had to take a job (or two) to manage their bills during college which meant that they didn't always have the time to be at the study sessions.