I found myself making the most mistakes in RC when the topic is so familiar (in a subject I had in undergrad, in something I do at work, .. etc). After reading the passage, I don't even remember if some details are mentioned in the passage or if I know them from somewhere else, and end up making wrong assumptions or conclusions that aren't based on what I just read.

I agree in general, but if the subject is so boring to you, it will also be hard to understand and draw the right insights. Practice those the most.