The path of the Gra is learning "beiyun" (in depth). To me it seems clear that learning in depth and review are related. Thus I heard in Shar Yashuv the importance of reviewing every chapter ten times.

And I took this advice with me when I went to the Mir in NY. [Doing each Tosphot that many times I found bogged me down, so I settled on doing each Tosphot twice, and the Pnei Yehoshua (a commentary on the Gemara ) ten or more times. The Maharsha I forget how many times I would review it.]

And I believe that this can be very helpful when it comes to doing Math and Physics also. However because of my late start in math and Physics, I decided to do the fast sort of learning [saying the words and going on] until I could get up to speed with the current issues in Physics and Mathematics. [String Theory, and the vast array of subjects coming after Algebraic Topology.]

My son, Izhak, definitely held with learning beiyun [in depth], and the way I see this is that in depth is not different from fast learning except in the amount of review.