There is no one answer. The main problem with taking copious notes is that one usually cannot also listen well, and hence spends the whole hour without learning anything. Then it is essential to study the notes carefully, preferably right after the class. If one reads ahead on the topic of the lecture, then one can listen more easily since one already knows most of the content. Then one can take notes on the new parts, or take notes for emphasis on the important parts even that one knows already, since less effort is spent hearing the lecture.
But there are many types of courses, some following a text closely, and others in which the professor is making up the presentation nightly from his own expertise. In this latter case one cannot prepare the material in advance. It sometimes helps here to not take notes in class, to listen as well as possible, maybe jotting down a few words, and then after class go to the library and try to write down from memory what has been understood from the class. Then one might try to discuss with a classmate what one has missed. This is very scary, since one is afraid one is missing things one cannot recover, while only listening. In practice this can work well, but it takes a lot of effort and nerve.
I seldom had this nerve, and spent years taking hundreds of pages of notes, all of which were eventually thrown away, mostly unread. The most successful classes for me were ones where I worked through the notes right after class faithfully, and perhaps wrote them up again. It also helps to discuss the ideas with peers and to visit the prof and ask questions. It is true that writing things out help the learning process, and one should spend as much time writing up explanations and working out examples as feasible, mostly outside class. Preparing presentations to peers is also very useful as is tutoring younger students.
When I really wanted to nail one class, I would study also alternate books on the topic, in addition to the required ones, to learn from a different perspective, learn things left out by my professor, and see more and different problems and applications. It really impresses the prof when you include a proof on the exam that he himself has omitted from the course.