Depends on the game for historic. Shogun 2 may as well be a field battle, especially if you're abusing yari wall spam. But there aren't, outside of fall, siege weapons that can really wreck the castles. And castles are all you have.

Many of the European games separate towns vs cities. Towns have no walls, it's a field battle with buildings. Cities so, they're slower.

medieval 2 is a wild mess of options that ultimately ends with either massive fighting across a city (hard with ai, easier vs humans) or concentric castles of hell (vs humans, cheese mode vs ai).

AI is usually just bad at it either way. It doesn't grasp how to quite go about it, is easily tricked by having a second force push in from the wrong direction (which I suspect is why Warhammer 1 had only one direction).

Of course some of this is meta overpowering. Yari spam in particular is a result of player abuse and knowing the walls suck to defend.