Polish(more commonly known as Compound polish in Pakistan) is only used to removed scratches and swirls.
It is very important to understand what a polish does.
A polish basically "cuts" away a very little amount of clear coat and in turn removes those scratches which the clear coat has.This reveals a fresh layer of scratch free clear coat which in turn shows the flawless paint beneath.
Now if you go overboard with the polish then you may end up taking away too much clear coat, leaving the paint susceptible to the effects of the environment.
So to answer your question, you should only use polish when you are about to do a paint correction and remove scratches and swirls, otherwise you could potentially remove a significant amount of clear coat(which protects the actual paint from damage) that does not need removal if there are no scratches.
Also, you should consider using the services of a professional detailer rather than going all guns blazing to do a paint correction.
A wax does not give shine.It is a common misconception.
A wax only seals the work the polish does, in plain words it keeps the shine intact.
If you don't wax after you polish, then the shine will go away quickly as compared to if you did wax the car.