It's not the writing device, but how it's used. I use one blue pen on the final pass of the notes, and review only what I underline on the morning of the test. Compared to people who either highlight every word but a,an, or the. Or, those who use 15 different colors to turn their notes into some version of an acid trip. I think that people do that and become distracted from the material. Also, when you highlight too early, you are likely to not highlight something important, then skip it later since it's not highlighted.
ddmo, Founder: Anti-Highlighter Club of America