For the first 2 years of Oxford, I went to maybe 4 lectures out of hundreds available. I was arrogant, foolish, lazy, and severely disadvantaging myself.
In my third year, I went to almost every single lecture available. Including those involving topics I was not personally involved or interested in.
My mind changed when I actually went to lectures.
Firstly, lectures are FUN! Sure, some of them suck. But I found so many gems that influenced my thinking. I found so many passionate, knowledgeable speakers who got me excited about the topic.
Second, I remembered more stuff! An hour in the lecture hall has massive returns on investment.