The answer really does depend on the situation. If you find yourself repeating the same code, look for a pattern or some commonality. In your example, in might make sense to define a base class that includes the five files. Then you can create subclasses as needed, and the files will already be required. Doing this assumes that the situations where you need to require these files share more in common than just needing the files in question, for example a series of reports that all use the same formatting libraries.
If classes aren't right for you, then yeah, you might just want an 'init' or 'common' file that requires the five files up front.
