I know that one of the ways that districts work is that they allow you to have specialized cities. In my game I had my capital focus on production and food because I planned it to be a military city (and science as well), and several of my other cities focused on faith, commerce, etc. Although I do notice that letting one city focus on one aspect doesn't contribute to my total output. With my capital focused on science I noticed that it takes me more turns to research a tech because of my total science output. Is there a way to have focused cities while maximizing the total output?