I’ve encountered two issues where enemies stay inside their assigned fence and it causes gameplay issues. The first, and most common, is that they are really easy to just pick off with a bow. They cannot come after me and do not even seem to know I am there, if outside their zone.
The other is that if I have to flee from a big group, they just cluster at the border of the boundary and make it extremely difficult to return, while also allowing me to depart at my earliest convenience.
The strict boundaries thing makes it so that the game is either too easy, or so that a given area becomes impassable until I return to Sacrament for a moment. Perhaps having a “likelihood of returning to area” radius outside of a fence could work, so that they’ll pursue outside their fence, but have a long tail over which they are more likely to give up the chase.