From a detailer who doesn't rely on detailing for full time income, here is my thoughts on it. My background, i have been detailing part time since 2013 and doing coatings since 2015. I do regular details but try to stick with coatings, I do about 5 per month. I've gone through 6 different vendors or manufacturers, whatever you want to call them. I currently use IGL and Pearl Nano, I've used Gtech, SPS, Feynlab to name a few others. I stick with these two based on my testing, a pickup that delivers travel trailers across the US, averaging about 200,000 miles per year. I coated his tailgate last year and check it about 4 months I think it was. He had driven 80,000 miles and 3 of the coatings were working very well still, a few ok, and some just sucked. The truck had been to Alaska, New Mexico, California and Canada so it saw all the weather. When i say "working" the coating was still dispersing water very well compared to others, showing some protection was still available.
Is a coating worth it, it depends. Some people love to wash and wax their cars. For these people no, it's not, you should not wax over a coating. In fact, when it comes to care, you should only wash with a "car wash soap" that contains no glossifer or wax. These products will fill the microscopic pores of the coating reducing effectiveness until the wax or sealant wears off.
The second person it doesn't really offer anything to, the garage queen. The one that sees no rain, gets driven to a car show and back, basically sees no time out. For these cars, a great show car wax is the way to go.
The daily driver or car that sees the elopements is more where a coating, IN MY OPINION, belongs. All of our cars are coated, I have a Jaguar F-Pace that basically is for winter use and long trips with lots of cargo or people. The Hellcat sees spring to fall, with some winter in Ohio when our roads don't suck. Cleaning a coated car is a breeze, between a leaf blower and a twisted fiber drying towel, you end up with a great looking car after every wash for a few years.
Every car I coat sees a chemical and mechanical decontamination. Since I do a mechanical decontamination you need to follow that with a polish. Are there guys out there that will clay a car and coat it, yep, they will say they leave no marring, sure,. ok, however many instructors will tell you that is false.
The next thing you will hear is "maintenance" for coatings. I've never had a car come back for "maintenance" since starting coatings. My opinion, it's how detailers make more money. Some will wash your vehicle then apply a top coat to it to boost the performance, not really needed but does restore the high beading affect. I provide my customers with a care pack, a drying towel, 2 microfiber towels and a small bottle of each of the things they need to keep their car in good shape, Some sort of quick detailer to remove bugs or bird crap, both of which will eat through a coating if left, tire dressing ,interior cleaner, interior dressing and window cleaner.
The other question is graphene. Is it worth it, is it better. Eh, graphene looks good, really good, I haven't seen any of the benefits they tout for it. It acts just like the other coatings I use. I did notice graphene did not last as long compared to the other coatings I used to test with. For some, maybe it will last longer, but in my test, it didn't
So, I hope that helps with some coating questions people may have.