The main impetus to break off some code into a separate routine is when:

• it takes more than a screenfull to show all the code
• it is a separate logical function
• it is called multiple times
• it makes testing/debugging easier
• i think i might reuse it elsewhere
• it makes an if statement fit on one line or just read better
• i get paid per line of code
• i think of a really cool name for it
• pfft... separate routines...