Imho, a controller should reflect a specific functional area, dealing with a group of features related to each other. For example, you can have a controller dedicated to user management, where you create and edit users, manage user rights, user profiles, anything related to your users, another controller for product management, where you display available products according to user inputs, manage stocks, suppliers, and such...
With too much controller you end up redirecting all day long, with too few controller it's a mess to maintain.
Of course, when i say"this controller manages that group of features", i don't say "put all your business logic here". Controller's duty is to call the right business method(s) and to pass this data to the right view.