Paint is sealed with layers of clearcoat.
Conventional wax was used to "feed" the paint.. But it's sealed now and just smears on the clearcoat.
The polymer based waxes bond with the clearcoat and last much longer..
Twice a year works for me.. I used to do the zaino thing.. But now use meguires NXT with great results..

if I am not mistaken it is written in owner's manual to top up wax if needed.

I use Meguiars ultimate wash and wax at least once a month and Meguiars quik wax at least once every three months.
Never wash or wax in direct sunlight and always drive the car straight after washing and drying.
Always dab dry the car and don't drag a cloth along the paint.

Get your car professionally Opti-Coated and you'll never have to wax it again.

you would still need to wash them though :P
and when it's really, really contiminated, you still need to clay them Orz

Personally, I wax one time per year--- before winter starts. That's all. I agree with other people's sentiments. Paint is well protected from the factory compared to decades ago. Keeping the car clean and garaged is more critical than waxing the car more frequently.

opti coat once... and never wax again

Opti-Guarded since the day I picked up my car 5 months. The car looks like it's been waxed and detailed even after just hosing it down with a pressure washer at home with nothing else! Really worth it.

I say typically Every 2-3 months.

I wax every night before i go to bed

Well on a new car I like to do it once a week for 3 weeks in a row then after that. once every 4 months