I have been recently hired to maintain a very large program (only two Activities, about a hundred Fragments, and several hundred layouts).
Maybe it is a too late answer but different programmers can take advantage of my answer.
Facebook's Stetho library is wonderful tool to see inspects for running apps. Stetho library works like a Chrome extension and it will similar for many programmers.
Also to see HTTP request/responses are very easy by using Stetho. I absolutely advice every Android programmer try.
http://facebook.github.io/stetho/