According to the Talmud there is a point in learning fast even if one understands not a single word. it says ''forever a person should be ''gores'' (which means saying the words in order and going on" even though he forgets and even though he does not even know what he is saying.'' And in fact it seems impossible to get through the  Oral Law without doing this. The Oral Law  refers to the parts of the law which were no written until the Mishna and Talmud. [It means the two Talmuds and the midrashei halacha and midrashei agada] It does not refer to any commentaries that were written after the completion of the Talmud. but the many commentaries come under the category of learning the Oral Law. [In depth learning also is important. SO one needs both a fast session and a fast session.]

Some Rishonim that hold learning Physics and Metaphysics are also included in the mitzvah of learning the Oral Law as the Rambam says in the third chapter of Laws of Talmud Torah that ''the things called     Pardes are in the category of Gemara'' and he [the Rambam] defined those things called Pardes in the first four chapters of the Yad haHazaka, and at the end of those four chapters writes ''the subjects explained in these four chapters are what the sages called Pardes.