The wax has to cure for a 24-72 hours before additional layers can be applied. Cure means that the wax must harden. If you apply 3 coats in one day, its basically one layer on the car. To achieve the best results its is recommended you apply the wax with a coat every few days.
The same goes for a polymer non cleaning sealant. You must wait a few days inbetween coats so the polymer can cure/cross link.
Two products are an exception to this, blackfire and zaino. These two sealants can be layered because tehy have an instant cure time, but they both are limited to three coats a day.
Now, this is for the best results, I have applied 3-4 coats of a polymer sealant (Klasse SG) in one day wiht no adverse affects, the results were very good. I even put two light coats of wax on top of the SG (two light coats to ensure complete coverage.)
As for the car, it has to be the lighting, and maybe the paint job.
Jason