Zaino is to be spread very thin, and dampening the applicator with water will ease in the application.
A dime sized dollop is good for an entire body panel, ie; fender, door, trunk, with the hood requiring a little more.
Also, if you're using the 2oz. bottles which come with ZFX, a good "barometer" of how much to use is 2oz. will easily get you three coats.
I've been using Zaino for a loooonnnngggg time, and this is true for most cars.
Ed