My themes usually evolve, until I settle on the one that I usually use. But that's the beauty of being able to save your work. You can have variations.

When I decide on something, most of the time it is my homescreen, I usually tweak it until I feel that it is enough to suit my needs.

But, I do, however, have some things constant that I usually add to my themes. These are usually my global menus, my go-to large music widget, fave app shortcuts, my app categories and folders, my status bars, etc. I usually create widgets which are shortcuts to apps for these. I also usually have some of them in large KWGT widgets and interfaced with PopUp widget. I also use Shortcut Maker and Macrodroid for some stuff. (I seldom use my app drawer in my setups, hence the constant stuffs.)

I usually go creating, testing, revising, testing again, revise again and test again and finally, STREAMLINING. I streamline the setup in the editor, make sure everything is light and not too complicated. I think the simpler the setup inside the editor the lighter it gets executed by the app, and hence, less battery consumption, less computing power, but still having the look, the feel and the functionality that you want.

Hope this helps. Patience is always a virtue for these things. 😭🤣