polishing the car wont protect the paint (won't give you the extra layer protection), it brighten and gives out the deep gloss colour of the paint. Waxing gives sort of like a condom protection on top of the car.
A good set of wax/polish shouldn't say how long they will last on the car. WHY?! all depends on the condition of the car,weather,indoor or outdoor,etc... IMO doesn't matter how much $$$ you spend on wax or polish as long as you giving the car some TLC thats all that matters!
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As for paint protection. My friend got the HSV with paint protection, and only 4wks new, on the bonnet couple of Tree Saps. He couldn't get rid of it, took it back and they gave him a special shampoo free of charge. I wouldn't spend $$$ on getting the Paint Protection. I would rather spend that $$$ and get a good set of detailing kit and one good weekend DIY :) The joy and pleasure of doing it yourself is just priceless! Plus if you have done it properly, your car should be HYDROPHOBIC (repels water off the car). Plus you can easily blow dry the car instead of wiping.