Occasionally people just learn things wrong. I do this a lot, and that's (hopefully) not (just) because I'm stupid (sometimes), but rather because there's a lot to one topic - more than can fit into a chapter of a university class. To mitigate this, I choose to do on one depth-first research rabbit hole or giant, topic-spanning wrap-up per month. Who knows, maybe there's more people out there who retain information better this way.