I live in New Mexico, hot dry, dusty conditions. I wash it 4-6 times a month. Usually ends up being a Rinseless or a full wash because of the heavy dust/dirt build up. I have not been through a continuous harsh environment. Been through two heavy winter storms up north and mostly heat. I personally think it has stood up well, considering most products break down after a few washes. I think the washes are probably just as bad as the heat and as many times as I have washed it, it has been good. It stays outdoors half the day, so it does get exposed to the sun a good amount of time. The hood has shown the most breakdown, probably due to the longer and higher heat temps.
As far as sheeting, this product is known not to sheet as well as other products but I think it does good. I hardly had any water to dry after doing my wash. Compared to my malibu which I am currently working on, which has no product on it, they are light years apart when it comes to comparing one with wgdgps and one with absolutely nothing. I should have taken a vid to compare like I wanted but thought no one would care. Lol
The manufacturer claims up to six months, in my conditions 8-10 months. I am happy with that. Longevity might not be up to par with what others are looking for, but the continued gloss impresses me and a good looking vehicle is what I want. Washing is super easy, bugs and road grime just slide off. This product also stays slick just like the first day I applied it. I am sure there are better sealants but not a significant difference to change at this time.