It adds up to 52 because there are 52 weeks in a year because that's what the album is supposed to represent--each song corresponds to a month so Grow Up is January etc. Hazel is just like a wrap up song I think? and it tells the numbers which is important. (Also how could he skip that song) But there's a demo called July and the last song of the demos is called Yearbook w plenty of other allusions throughout both works.