So on my current WRE playthrough on Normal difficulty I have full stacks all along my Balkan/Alpine border. Augusta Vindelicorum all the way to Sirmium. There's ten stacks of Huns all trying to get into my territory, but none of them have the stomach to engage my towns, even though in some cases they outnumber me four to one. I get that a full stack in a town isn't exactly a walkover, but surely the Huns aren't so intimidated by opposition that they don't dare place their 80 units, ten of which being heavy onagers, against my measly 20 units behind dirt walls and barricades?
In fact, this has proven a vital strategy in securing my WRE in the first hundred turns. Don't want enemies crossing the Alps? Camp armies in Verona and Mediolanum and they'll turn right back around. Want to kill armies without wasting a soul? Easy, have the CAI dither around in snow attrition while you sit comfortably behind town walls.
I get that Normal difficulty isn't supposed to be like Legendary, but I consider it fairly normal for armies with numerical superiority and siege equipment to take the fight to small towns, or poorly developed cities. Because what this is doing is ensuring a stalemate that does nothing to the benefit of the player: the enemy camps outside your towns in large groups, and your one single defending army isn't enough to take them all on. If, through some miracle, I do manage to get enough armies together without exposing the rest of my border, the CAI calculates odds and as soon as they're in my favour they hightail it -through- my ZOC and right out of my range of pursuit.
The idea is that I -want- the CAI to attack me. I have my armies posted along the border as a strategy to slowly wear the enemy down through their failed sieges. That allows me the opportunity to retaliate. Instead, nothing happens. Turn after turn after turn.