I've seen "breeze through homework" for one of my child sims, in addition to "dominate homework" (with that one he hardly has time to open the book) I've never seen these for my teen sims though. (My teens don't often do all of their homework though, so I might just not have seen it yet)
Does the boy that takes his time have the lazy trait? Maybe that makes a difference? Or perhaps he's a perfectionist? (Being a bit of one myself, I know it used to take me a bit longer to do my homework, due to double checking everything. I've re-wrote this post 4 times before submitting it :# ) What are the other boys' traits?