Games : How to you use districts efficiently?

I am pretty new to the game, and while I have understood most of the key concepts, I am not quite sure how to use districts properly to manage my city. Honestly I find the whole concept of setting and managing districts quite confusing and overwhelming.

• Is there any benefit of using many small districts for residential or should you for example just combine all residential zones into one district?


• Should you combine different zone types (residential, commerce, industry) into a common district or is there a benefit of keeping different zones in different districts?


• When would it make sense to use district policies like energy saving only for some districts but not for all?

If you could shed some light on how to use districts properly, I would be very grateful.