That was my MO throughout high school and college. I watched countless students buried in a laptop or (paper) notebook furiously trying to keep up and undoubtedly not even processing phrases or sentences. Of the people I talked to, most were convinced that it's better than just listening, but I suspect they would find their memory is a lot better if they're actually comprehending strings of speech longer than two or three phonemes.

The only exception for me were courses that were heavy in symbolic manipulation, like calculus, statistics, and relational algebra. For those, the concepts are still easily gleanable from the textbooks, but I found that it's very helpful to follow along with the teacher on paper to practice the physical manipulation of symbols.