I just did mine. Previously I tried Mequire's marine wax. The RV did not shine and even looked blotchy. I hand rubbed in a second coat and in places tried a third coat. The results were no better.
I had to use wax stripper and then soapy water with ammonia. I then went over the whole unit rubbing with bar keepers friend. By comparison the Zep went on quickly with no rubbing or work. I stopped at 4 coats which took about 3 hours to apply. The RV now looks good and shines in the sun. I hope it is now also easy to keep clean.
If the internet reports are correct, the finish should hold up for at least a year, then a good wash and another coat or two should hold it another year. We will see.