Each sealant or wax is different in how it bonds with or 'sets up' on the paint. Zaino, for example, requires that you do the whole car and then ensure that it has had time to dry before you buff it off.
I've found in the past that some of the cheaper waxes become really hard to buff off if I let them sit for a long time.
You will follow the manufacturer's instructions. And you will like it.