With past experiance.........If you don't buff them out and apply wax as a final coat,...You'll be doing this process again in a few Sun Blazing months.

If you sand a piece of plastic, Your creating little pores in the surface.
After a while the pores dry out(Oxidation) and collect fall out/debris, This makes the yellowing on the plastic.
If you High Speed Buff the palstic after wet sanding.....The Heat from the friction of the buffer pad and the wax seal up those pores which create a crystal clear and smooth surface.
Same idea when you Buff the clearcoat of a car...


G/L