Can you max every building before moving to next city?

I haven't been able to muster the patience to fully max everything in each town to see if there is a secret trophy or reward for accomplishing that. I think maxing everything might not be encouraged because it's not desirable. As I get closer to maxing, it causes workers to pause since raw materials becomes scarcer.

From my experience, all production buildings have two upgrades. The first is a scaler for resource production, and the other is a reduction in the production time per unit. It appears that zone-to-zone level limits are different. The buildings have a cap on the first upgrade (the resource production scalar). I have yet to hit the level limit on the production time upgrades.