longer depending on what grade of wax u used from swissvax.
in the 'top tier segment' of swissvax there are 3 waxes: concorso (S$380+/200ml), mystery (S$700+/200ml) and the legendary crystal rock (eye watering $1750/200ml and used by paul dalton who is the world's top detailer)
they each have very high carnuba content and the concorso one easily last 2-3 months, the top grade crystal rock can go 6-12mths on one application.
mystery is a little hard to work with as its an older formulation so tend not to use it.
being a wax and detail freak, every 2-3 weeks the car gets a polish. Am on concorso and have gone thru a tub in 2 mths.
for metallic silver the additional visual effect of crystal rock over concorso does not really increased significantly as compared to a car that has pearlescent black or red paint.
here are some pics of the car waxed to the max again. (even the glass is polished cos there is dedicated glass polish too, sadly not Swiss Made)