I like the idea of changing the speed and length of punches because it can catch your opponent off guard.

If you think of it in baseball terms, no pitcher goes up there and just throws fastball, fastball, fastball and if a pitcher does throw nothing but fastballs they change location and type to keep the batter off balance. You cannot throw the exact same combination all the time and expect to land it....look at Campbell-Funeka. Nate could have finished Ali Funeka off had he changed up what he was throwing....feinting and throwing a left hook wouldn't have been a bad idea at all.

You have to figure your opponent no matter how dumb will eventually catch on to what you are throwing so sit down on different punches in your combinations.