Parent was writing about a university LECTURE which is different from a TEXTBOOK (which is different from primary sources), so yeah, consulting other sources is checking the facts.

Oh I see what you're saying. It was slightly ambiguous.

But in any case, I didn't read a single textbook at uni; it was all lecture notes provided by the lecturers (fill-in-the-gaps actually which worked waaaay better than you'd think). So the answer is still no - I didn't fact check them and I didn't need to because they didn't wildly hallucinate like AI does.