Personally, I use modules whenever I can if the following conditions are met:

1. Deadline is short (i.e., I have a deadline :-) )
2. I know the module is quite robust, maybe overkill but useful for the problem at hand
3. I have 'bigger fish to fry', i.e. the module solves a problem so I can concentrate on the 'main issue'
4. And sometimes, I don't know an efficient way of solving the problem but someone else already has

In case #4 the module route just gets things working then I can go back
and actually learn what I need to in order to solve the problem myself

-felonious --