Absolutely true, and writing down 'cheat sheets' of such summaries was one of the most effective ways to learn. But I simply did not have the understanding yet, within 60 seconds of being presented new material, to be able to write a good summary of it. And at the same time also write a non-summary, in the likely case that things would not be clear from the summary alone when reviewing. And do all of this before the lecture moves on to the next thing that needs first understanding, then transcribing, then summarizing.

This is why one attends lectures, reads the book, takes notes for both, and then assembles a summary.

It's called studying.

Yes. And is studying more, or less efficient, when lectures are spent focused on transcription, instead of the material?

In lectures, focus on the material. When working from the book, you have oodles of time to transcribe. Hence, both modes of learning.

For some lectures I follow the course in class. For some other lectures I just read the slides on which the lectures are based and go in depth on my own. Some other friends follow all the lectures. Some others just don't follow that much.

I don't know why you provide a one method that should fit everyone, while everyone has a preferred way of studying that isn't necessarily the best approach for other people

Because the lecturing professor assigned a textbook, making both lectures and the textbook relevant to the course.

Also, it's at least three distinct methods! Read before lectures, read after lectures, read on both sides. Dealer's choice. Neglects recorded lectures and the possibilities they open up.

Talking about people's preferences and studying is funny. Most people prefer not to study. Preferences have little to do with good study habits. The above approaches have worked for hundreds of years just fine.

Well, of course if a textbook is required to be read, you read it period. I was talking about different study methods in the bounds of what is allowed to do

Yeah but depending on the pace of the lecture you might not even get everything down. So it's better to take some notes after class like this