What is the best practice for styling my assets?

For the majority of my screens each asset (i.e. button, label, textarea, etc) uses local styles to achieve their desired appearances.

I was wondering what would be the more optimal approach to styling my UI, would it be to create a unique style (lv_style_t) for every asset that has a unique appearance?

Eventually, I would like to add a custom dark mode option which will require me to change the appearance of the assets when activated. This would be more difficult to implement when local styles are being used since they take higher precedence when compared to using regular styles. Any input is appreciated!

Check the default Widget demo sample for ideas.
If its for changing colors then you can change accent colors. If complete change required you can use custom themes.