By doing 12 coats now it will reduce the amount of sinking that the varnish will do in the next season and so reducing the need for a new coat of varnish the very next winter.
If you were a Riva owner and you spent all that cash and then found you needed to varnish again the very next winter you would think the builder had ripped you off.
So the reason you were told 12 coats now is for your own good unless your happy to varnish each year as lots of people are !!
It does cover over the dumps and scrapes of the season.