Personally, I think it greatly depends on the color of the car, climate, etc.
It was made VERY obvious to me last night, that we had not been prepping/waxing our *white* truck very well these last 4yrs, mainly because it never really looked bad, i.e. white paint.
Until we had it sitting next to another dodge cummins WHITE truck of the same year, major difference in paint texture & overall cleanliness. And we do keep our vehicles VERY clean, compared to most - or so I thought, hehehehe!
In the last 2 days, we used Nufinish Polish, shined her up real good, let that cure for 24hrs, followed by Mother's Synwax last night - BIG DIFFERENCE! That truck's WHITE now.
One reason we had not taken as much care of it's *color* - if you will, is because we didn't realize the difference versus say a rich, deep color.
For our 2 burgundy rigs, I've always been more cautious about waxing them at least 3 times a year. But again, I'd never thought to use an actual cleaner wax, specially after our harsh winters, prior to waxing.
So, from now on, every spring, all trucks will get a cleaner/polish wax treatment, followed by a good synthetic wax. Then, just before winter, I'll put on a good coat of synethic wax, wait a few days, and do it again.
This magnesium chloride is wreaking havoc on the 2 richer colored vehicles.