It was a mix between making it much harder to organize all the levels, and pure laziness not wanting to write out everything.

Basically, each level has a phrase in the album picture area on the left side of the song. I used this phrase (since they were generally unique) to identify each song. There are only like 3 which overlap, and two of them are the same exact song and everything. (I'm not sure if they are EXACTLY the same, but I'll investigate when I get the chance.)