There are many factors that affect this:

1) The complexity of the App. If the App is the next MS-Word or Excel, there's no way I'm stuffing all the code in the Form. On the other hand, if I'm making a 'Hello Word' App, I wont put it in a module.

2) Resuable code. If I need to call a saving routine more than 2 or 3 times, it's easier and more organized to use a standard module and simply call the function from there.

3) Size of code. If I only need to call a function once, but it's over 200 lines long, I would rather place it in a module.

4) Orgainzed Code. If I need the coordinates of 5 rectangles, it's much easier to create a Class Module or UDT for them, than to have 20 variables.