In a modular source code structure, e.g. in Zend Framework 2 applications with third party modules, files tend to be nested in deep directory structures. Opening that
vendor/provider/module/src/Module/Mvc/Controller/AdminController.php requires e.g. 9 clicks plus looking for the right sub-folder at every level.
Enter smart navigation. If you're more or less familiar with your codebase, most of the time you know exactly which class or file you're looking for. An IDE worth its salt will provide you with a MixedCase smart navigation tool which makes navigation a lot more efficient. In PHPStorm 6 for example, you hit ctrl-shift-n which opens a smart navigation tool:
MixedCase typing (enter e.g.
AdC) will be matched with your source code files on the fly and provide suggestions.