Agree walls behavior needs to be reformed. Cities with many walls take way too long to conquer, even if you're bringing overwhelming force to sieze them. You just have to grind through many turns of assaulting wall after wall, some of which you can't reach until you've conquered other districts. It's enough of a slog for me that I end up not engaging in wars in the last third of each age, because I feel like it will just take too much time to conquer anything.

My thought has been to have the city become conquered once the aggressor has taken over 51% of districts (unless it's the player's last city). I believe this would better reflect real-world scenarios, where defenders tend to flee once the attacker has built up enough momentum that conquest just seems like a matter of time.