My personal suggestion is to always work with symbols: if not you work twice! I wanna make tutorials about it: I developed a technique in which, using multiple timelines, I adapt the object to the context.
This is how I structured my website: www.360fun.net
You can see how the same symbol "universe" and also the others adapt to mobile and desktop, and if I change something, it changes in both versions!
I also use a lot the flexible layout with the "Zoom Contents" option, so everything inside a group adapts maintaining the absolute positioning.