The custom modules on the main site I work on evolve. I try to separate their functions and write multiple modules based on discrete needs but sometimes they grow into each other once written.
Now I have two modules that are inextricably linked to each other to the point where each of their .info files have
dependencies = theothermodule in them to remind future site admins of this fact.
Of course I can undo this and separate the functions out, but thinking about it made me wonder why I should do it, and that advice on this topic might be useful here.