It's a good strategy to compartmentalize your customizations as much as
possible.  This allows you to easily:
 * Turn on or off a customization.
 * Share some of your customizations with others (and keep some
   customizations private).
 * Move your customizations to another host and, if your host-specific
   customizations are in a separate file, easily change those.
 * Debug customizations (e.g., you can turn everything off but what 
   you are trying to debug).
 * Manage your customizations - small files are much easier to edit 
   than one big unwieldy file.

Some parts © 2009 Advameg, Inc.