Turning out to be long sub project!

Just now starting to work with Subtitle Workshop. I'm realizing very quickly that it's a good idea to check your sub in that program before you go including it in an authoring project.

Anyway I found this thread on here that gave a basic set of instructions for updating and syncing, but I'm not sure I did everything right!:

http://forums.afterdawn.com/thread_view.cfm/762694

According to these instructions I was to find the first out-of-sync flaw, then highlight that line followed by all of the subsequent lines, the click the double arrows icon to bump everything up, then click save.

That all went fine and I didn't have to anything else with the first subtitle I edited, but with the second sub I was playing around with I quickly saw that I was going to have to end up re-syncing every 2 minutes! At that rate it would take me all day to totally re-do a sub.

Is there a step I'm missing here? I thought that once you identified a problem time and clicked the double arrows, that bumped everything up and your re-syncing project was pretty much over!