When applying a spray polish how much do you use?

[cfiiman]

I know this seems like an odd question but it hit me today when trying to clean a very expensive Lexan (I think) custom window package on a special car I had them built for. When say using Plexus or Original Bike Spirits (Formerly Honda Polish) or something similar on them, the directions always say to spray and then wipe/polish, etc. But I got to thinking, if it is like washing a car you would need a full 100% covering would you not to avoid any potential scratching? Am I thinking about this in the wrong way? I usually see people spray a little bit then start polishing a panel, that just doesn't make sense to me b/c what about the areas that don't have any of the polish on them yet when you start rubbing? Does this question make sense? Yet it seems wasteful to coat the whole panel in a spray polish, it just goops up on the rag, so where is the happy medium? Is it best practice to apply it to the rag first, then lightly to the panel or ??? Thanks for any input, I just coated the windows to be safe b/c they are really expensive custom pieces, but I think I'm using waaaaaaayyyyy to much as most was soaked on the rag