AI does not seem to like exceeding force limits under any circumstances so if he's already built up his army to the limit and all of it is stuck where it can't do any good, the war is basically over except for the micromanagement. May cost you a small army stack each time you do it, but hey, it's worth trading a half-dozen weak infantry companies for winning a war against a much stronger opponent. Actually seems pretty reliable as long as Venice doesn't form an early alliance with another naval power you can almost always beat them at sea right away, and tricking the AI into following you onto blockable islands is not extremely difficult.

It's the hot new thing for a Byzantium opening, the so-called Budget Monk strategy (after a youtube poster who recently demonstrated it).