DH appears not to need to study, because he has a strong linguistic memory, more for written language than spoken, but he can often quote large sections verbatim after one hearing or one reading. He easily picks out what the author or speaker felt was important, and consistently remembers it, again, mostly verbatim. I don't think he even bothers to highlight. He's in math, and I've noticed most mathematicians I know seem to have a similar ability to rack up a lot of data really fast.
I need to study like hell to memorize data. But I have a much better functional sense of the material after one read-through.
He always thinks he's doing something wrong when he starts trying to do the stuff that comes easily to me, because he has to work almost as hard as I do to do what comes easily to him
And he has to do many of the same things to get there.
So there's a whole other dimension...
How you intend to USE information is important in how you study it -- but also not necessarily consistent from person to person.
