I think math and English take at least 60% of the time, and the others add up to 40%.
One is that math and foreign exams are right if you get it right, and wrong if you get it wrong (except English composition). Unlike other subjects, which are very subjective, you can write something even if you can't answer, and you may be right when you walk. Sometimes you think you got a good answer, but your score is very low.
Secondly, the scores of these two subjects are higher than those of history and politics, so it is appropriate to spend more time on these two subjects.
In addition, liberal arts students generally have difficulty in learning mathematics, and they still need English after going to college, so they should learn more.
The remaining subjects take longer, and history and politics are equally divided.