gettext best practices?

When using gettext, is there any advantage to breaking your
translation down into modules?

I was working on the basis of having a core.en.mo file for my "base"
system and then adding translations for each given controller (e.g.
frontpage.controller.class.php would add frontpage.en.mo to the
translation object, I'm not using Zend_Controller by the way).

However, the recommended translation management tool seems to insist
on scanning entire folders of source code to generate translations, so
I end up with a single catalogue containing everything in my project.

Is there any advantage to breaking it up? Or is that a disadvantage?
Does it load and parse the entire mo file? Or just use it as a
database to look up translations?

Cheers,

--
Michael Jervis
mjervis@...