One cheat of the AI's is the "run around till the battle timer runs out trick
One good reason why I don't play with the timer.

Well, I'll add another...........

Playing as the Greek Cities, I was making an effort to send the Brutii back to their own side of the "pond." The Macedonians had been pacified already so it was time..............

I had Appolonia under siege with a small garrison contained inside. Next to my besieging army was a Brutii general (and a pretty good one too) and one infantry unit. To cut down on the chances of a successful sally, I had my assassin kill the general. I figured without a general, less chance of success.

Or so I thought The next turn, there was another Brutii general to replace the one I had assassinated This happened for three, count 'em, three successive turns......every time I killed one another took his place. And no they weren't being shipped in or walking in from any adjacent area. The AI had just decided that that small unit needed a commanding general

I guess, in the end, it was good training for my assassin