My son Izhak held with learning in depth but also fast learning,--- that is fast learning in the sense of Rav Nahman of Breslov --to just say the words and go on. Even though I only heard Izhak state the importance of in depth learning--i.e with lots of review and deep understanding, he also held with the general principles of Rav Nahman which certainly includes fast learning. And I do nor mean this to apply to learning gemara only but also to mathematics and physics. [we know that these are also important a stated openly in the Rambam--in the Yad Hachazah [Mishne Torah] and in his other writings.]  but some will complain that not everyone has the math gene--but so what? We do not say that everyone is talented in understanding the Gemara, and yet everyone is obligated to learn and finish the Oral and Written Torah at least once. Learning Torah is a commandment that applies to everyone as the Rambam  puts it, '' young or old, even until the day of death..'' This mitzvah has nothing to do with how smart one is. So also for math and physics and all the seven wisdoms that the Gra and Rambam and other Rishonim hold are obligatory.