She did the challenging stuff she cares about. One aspect of nerd brain often is that you can hyperfocus on challenging stuff, but can't get the motivation to work on stuff you don't care about - and even what would be a 20 minute task can end up taking days because of that. It's great that she has the self awareness to set goals, and step away once they're done.
I didn't have that in that age - and still sometimes struggle. I was lucky enough that my employer back then recognized my issues, and paired other people with me for doing the stuff I was not interested in, and now usually manage to load those issues onto other co-workers by myself.
(Mind you, I'm not talking about a matter of inborn temperament or character, much less a moral flaw! Rather, finding the compelling challenge even in "boring" tasks is a valuable skill and situational tactic that anyone should explicitly learn about and aim to acquire as part of becoming a mature professional, not a matter of morality or somehow being dismissed as "lazy"!)