Disagree. Unless all his builders are busy for the next 5+ days, I wouldn't leave an extra builder to upgrade his walls. His walls really aren't that bad.
The only thing of concern is if all his builders are busy for 5+ days and he's farming a ton of loot that can't be spent. Then it comes in handy to do a few skulls here & there.
If I was him I would keep all my builders busy for the near future.



