I tend to use this tactic where possible, especially against heavily fortified cities with large garrisons. I suppose it's kind of an exploit really, but large-scale sieges are so bloody and time-consuming that I tend to try and avoid them wherever possible.

And yes, it will work against any level of fortification. Just make sure you don't allow too many enemies to escape. In particular, any enemy family members/generals must be eliminated on the battlefield, or they'll get back to the city no matter how heavy the losses are.

Antagonist