IMHO, if you feel contaminants in your car's paint that a mild cleaner wax like #66 can't remove, the next best thing to do is clay the affected area, then rewax it.
I think the amount of cleaning/waxing is down to each person's standard. If you feel your car is not clean or needs wax then wax it. If based on your standards your car is clean then don't clean (with cleaner wax/clay) it, QD it to remove fresh contaminants.
Here in the Philippines, the environmental condition is one heck of a problem, just like what theveed said. It's really bad.
In my standards, with the environment problem and being a daily driver, I wax my car every 2 weeks. I wash the car atleast once a week (more if it rains), and QD everyday to get rid of the contaminants. I believe that QD everyday or every other day keeps the contaminants away, lessening the need for claying. I have clayed the car about 3 weeks already, and as of this morning on my QD session, there are no areas that need claying.
Wax here does'nt last very long, about 2-3 weeks max! Although using polymer sealants/glaze would make your cars protection longer, it aint gonna keep your car from being dirty. Don't get me wrong, polymer sealants like #20 works well. I think with our condition here, doing #7 and #20 every 3-4 months you'd do your car good. What do I do in between to clean the car? I use wash, QD and wax (once a week or once every 2 weeks).
IMHO, Meguiars #66 is good for cleaning. It works well especially for white cars.
All I'm saying is, everything is down to your standards. If you think your car is clean, then it's clean, if you think it's dirty, then do something about it.
