I've been thinking about this layering thing a fair amount and I do have some issues with it. My problem is with the sealants and how they work. Apparently sealants can be removed in the same way that waxes can, such as using a 50/50 mix of IPA/water. I'm going to assume that mineral spirits, naphta and the like will do the same. So...this is where I see the problem. All waxes are dissolved/softened/liquefied with some sort of solvent, and that solvent is more than likely capable of dissolving the previous layer of sealant, just like it can dissolve the previous layer of wax, thus the resulting in a maximum thickness of wax and or sealant on paint no matter how many layers you put on.
The threads on this topic (on Detailingworld) have already confirmed that additional layers do NOT build thickness as far as waxes are concerned, though the sealants have not been tested to the same extent.
Waxes such as Collinite 845 use some form of mineral spirits/turps/naphta as the solvent for the waxes (based on my nose) and most other waxes use something along those lines so I just don't see how the sealant can survive intact underneath with all that rubbing and such. If sealants were not affected by these things, I think we'd have a dickens of a time getting them off, something that does not seem to be a problem, nor does it require anything special in the way of solvents.....
Just my two shekels worth....
Regards
Christian