With reagard to Facebook app I guess the problem is that they have too many resources, i.e. gazillion of people working on different parts without even checking

With reagard to Facebook app I guess the problem is that they have too many resources, i.e. gazillion of people working on different parts without even checking what others are doing so you get a bunch of duplicated, triplicated, whatever, code, a bunch of dead code and stuff like that. They also use some kind of generators and run into problems like having too many classes for Xcode to handle. From everything I've heard of it you don't want to do things the way FB does them with their app.