NOMAIN in Inquiry Module Question

I'm a little uncertain on when to use 'NOMAIN' in a module.

I've got a group of inquiry modules where the User selects a record from a
SFL and depending on the option it executes different modules.

Then from these modules the User can go down more levels. At each level a
different module is executed.

I realize by using a 'NOMAIN' module I should be doing the opening and
closing of the files including the display files, so I created exit routines
to close all the open files from the modules.

Now I'm looking at all this and wondering when your working with interactive
modules should I even be using 'NOMAIN'???

Thanks
Andy