I played through all civ's. This is probably a game that ate most of my gaming time. And i think it's because of the same thing as for you, that you are building a most efficient system for your goal. Recently i discovered "Factorio" and i think it will take over the civ for me. And steel even more of my time :(
Edit: be warned, it's really addictive...
Long ago I lost the ability to find mindless enjoyment, what I look for in games, in management-type sims such as this. They stress me out too much with the endless options and tweakings.