What you are looking for, is called a Spray Wax.
It's a very easy to apply liquid wax. Traditionally, waxes have been in paste format. These new breed of waxes are liquid based. They are sometimes also known as SiO2 (Silicon diOxide) based.
The most important thing is their application. You spray them on and buff off. Literally.
How often do you use them, is upto you. I am in Australia, and it is nowhere as dusty as Pakistan. However I use my spray every I wash my car.
Is it over usage, sure. May be not. Who cares? It's better to be more, than less.
I used to use the Meguiars Quick Detailer earlier as a drying agent. Since 1 year, I have been using the P&S Bead Maker. It gives me a beautiful finish and very slick to touch paint. My cars are waxed to begin with. This is more of a regular top-up.
