hehe, I'm the same way. I've only played the AI, and after a couple campaigns I always quit after three months of action, because I'm winning and know what the AI is going to do.
My last two campaigns, Scen 19, I quit at the end of July 42, becuase I had fortress LungaVille going, 5 US carriers at the bottom of the sea, and only one damaged Ziuikaku on the way to Tokyo. So all I had to do was park my carriers 10 hexes away from noumea, and port attack anytime there was clear weather.
My other campaign as US, well I had sunk 5 Jap carriers by Sept 42, and had a firm grip on PM, Gili-Gili, and Lunga.
I was going to win the points battle either way, and didn't feel like slogging through 15 more months of AI.
So I thought I'd fire up a PBEM game with someone, because then it's an actual battle against a human being.