I can focus for hours straight in a quiet room but:
a) I can't choose what to focus on. So if I need to do something but it's not the latest thing I'm obsessed about, tough luck
b) Deadlines help but if it's not something I'm obsessed about and there's no deadlines, not going to happen
My experience maps the author, I did well in university because becoming super interested in a subject and reading everything about it for a couple of weeks to the detriment of everything else worked well. Well it worked well in France where we had 2 exams a year and all exams were open book, it didn't work that well in the US where tests were more regular and memorising random uninteresting fact was expected (I lost point in a computer graphics class for not being able to give the name of companies that were members of the Opengl architectural board or when the first version was released... Who cares??)
After graduating, I'd say the fact that I get very interested in things and completely focus on them actually helped me in my career. On the other hand, my inability to do paperwork, send invoices on time (been a consultant most of my life), do my taxes etc lost me around 150k so far. So, it's a double edged sword for sure.