I wasn't sure if I was just imagining this, so I looked up the number of musical numbers in the following musicals. The musicals I selected are pretty much at random, whatever came to mind. I didn't bother to differentiate between orchestra only or singing numbers, b/c I haven't seen all of these. I just counted the number of different items listed on Wikipedia.
|Musical||Number of Musical Numbers|
|The Sound of Music||26|
|Phantom of the Opera||39|
|My Fair Lady||24|
|The Book of Mormon||22|
|West Side Story||27|
So I guess I wasn't imagining things, there are just way more musical numbers than the average musical.