My turkish campaign is on turn 100 or so, and I was having a hard time controlling the pace of the game, until I developed my "DMZ" strategy.

What I've done to slow the game down is determine early in the game which provinces I intend to hold long term (these are regions I intend to keep as part of my 45 occupied settlements.) For these settlements, I proceed in a calculated manner and heavily favor occupying unless my economy is totally strained. But, if I am attacked by a faction owning provinces other than the 45 I intend to hold, I fend of the attack and counter attack -- except instead of occupying, I exterminate or sack, and then destroy all of the settlements buildings.

After this, I either let the settlement revolt and attack again to get extra sacking income, or I gift it to an ally. I've found Russia to be a particularily good ally for this, they don't seem to be that aggressive, have no other allies and have been embrolied in a long struggle with the Poles anyway.

The DMZ strategy has some good advantages:

1) After launching a full-stack invasion, the AI is generally pretty weakly garrisonned, but will rebuild quickly if you don't counter attack quickly.

2) Taking and holding their provinces will spread out your garrisons and make you weak, and if you up your production to compensate, it will weaken your economy.

3) Destroying their buildings cripples troop-producing capabilities in cities on your borders, so even if your ally loses control of a border city, the faction that wins it isn't usually left with much. (Pre-gunpowder, I'll often flip castles to towns just to further hamper troop production.)

4) Sending border cities through the sack/revolt/sack cycle more than pays for the army that does the heavy lifting, and is a good cash infusion.