When I played the game for the first time (it was RTW back then), I was very careful and prepared every offensive step twice. It didn't take me long to learn that the AI was not that aggressive. So I soon started taking more risk.

If we were able to play the campaign against a human player and still employed our same old anti-AI strategies, I'm sure we'd get our a*s kicked:
Leave a town undefended for 2 turns? No problem. The AI stack nearby would never bother taking it. Sitting three miles away in the woods is far more relaxing than keeping the enemy population quiet.