I figured out the system mostly independently, because the senior developers were always under fire due to the over-large workload for our team. So while other interns would need help for an hour or two every few days, I'd ask something about the data type of a certain value in a function and be on my way. My mentor was especially impressed, but he was the only one because nobody else saw how much code I was writing or its quality. They would just see me getting up to pace about when the problem was very difficult, or opening up hn when I needed to give my brain a break.
Long story short, my manager said that they weren't going to hire me full time, which came as a shock because I thought that producing quality code to the deadline was the important part. He cited early mistakes in writing documentation (I'd never written a functional spec before the internship, but I posit what I eventually produced was of the highest quality) and my perceived lack of motivation. This despite me working as well and energetically as I ever had. I decided to look at it through a lens of another article I'd read on HN: Any company that doesn't want to hire me is a company I probably don't want to work for.
So while I'm dismayed that this pattern will continue, it's nice to know that there are some people who know the difference between a good programmer and one who puts in overlong hours.