Imperator Knoedel
Currently obsessed with The Owl House
New commit: Cottage economy? Specialist economy? Why not both? Build a city hall and never worry about anything ever again! 
Too much work for questionable gain.

Make a fort in the cityradius a prequisite for a castle.
Maybe put a cap on the amount of free specialists the castle gives ?
The cap could be raised (a little) by a building that needs four castles (like cathedrals)
And two (world or national?) wonders.
One wonder could raise the cap even a little more (by one)
And another wonder could remove the cap (for one city) alltogether (Krak des Chevaliers)
Too much work for questionable gain.