Depends on your context really (one could expect different page types to have different JS, so each page type could easily have it's own autoptimized file). let's say that anything below 100 js-files seems like normal behavior.
I've compared the HTML of 2 "features"-blogposts and at least those 2 refer to the same aggergated JS-file (http://3m6ok5roj7q1lfxor15yilh164s.wpengine.netdna-cdn.com/wp-content/cache/autoptimize/js/autoptimize_3bf91e48539bd79953692bae2cba6dac.js), so that's a first indication there is reuse of the same file across different pages (blogposts).
frank