The gradual increase in the strength of tint, on each separate side glass, results in a better graduated transition when viewing the car from the side.
I had my previous ZS EV Gen1 fairly strongly tinted from the “B” pillar back.
As we know the Gen1 offers no factory tint and therefore no UV / heat protection in the cabin.
Dark tinting from the “B” pillar back is a big improvement, however when viewing the car from the side, it almost gives the impression it is two cars stick together ?.
This because there is no gradual transition stage.
it’s clear glass in the front doors, then “Bam” heavy tint right alongside it in the rear door glass !.
It’s a bit of a brutal cut off in my mind.
To this end, when we upgraded to the Gen 2 model, it did come with a very slight factory tint.
It was okay ( ish ) for the front side glass, but did not offer enough protection to the rear side windows and rear windscreen IMO.
I used the same tint guy for both cars and said I wanted the tint to be more gradual this time around.
He did the rear screen with a heavy tint, then stepped it down in the rear side windows.
The front side windows were left in the factory tint.
I was really pleased with the results, what ever angle you view the car, it just looks right somehow ?.
I think it gives the best compromise of protection without any legal complications.
The tint guy I used has been tinting glass for over 20 years and refuses to tint any glass forward of the “B” post.
It had been a policy he will not deviate from.