Im a meguirs man. Maybe a little middle of the road. I used to have a small mobile detailing company. Is it Garetts garage? Ill lool after posting stuff. Thats top end ferarri status.
First and foremost. You wont need clay on a new car, or shouldnt. At most some sap or something may be on it. In which case 3M makes a prep liquid product that will remove any waxy type substances. Clay goes a little deeper to stuff actually ground into the paint.
If you do you clay, you can get swirl marks. In which case you may need to polish after. I like meguirs #7 for that.
As far as wax. A good long life is the pro model with a polymer in it. I just used that on my new car.
On moms car, the one step cleaner/polish/wax. 8 bucks and does a good job. Next time I'll go over anything with clay, then #7, then the polymer.
If you want a really nice shine, and like to do it often, i would go clay #7, then #26 high tech wax. Probably similar to the harley stuff.
Any cleaners, compounds, etc may leave swirls. But meguirs makes stuff #1- infinity almost. Gotta research your paint type and what works best.
Maybe they are talking about a different kind of clay than im thinking...
In regard to letting it sit to long, I work in the garage, and make sure it dries. Just hazy, but if you have a machine polisher. I have the harbor freight grinder type 10", and a 6" orbital.
I knock off most the wax with a terry rag. Dont try too hard. Repeat over the same spot lightly as opposed to pushing hard once. After its knocked down, I go over it with a wool pad and orbital. One that spins off center so you dont burn the clear coat. Not too fast. You can use the kind (excuse me not remembering the name) that spins like a grinder. Really easy to burn the clear coat. Tell your neighbor or mother in law you will wax their car to practice [emoji23]
Once you get it down, its easy. Once im just removing a little wax I spin that thing so fast I've had the wool pad blow apart. Not recommended.
Then i go over it with a diaper (detail type rag) for any tidbits.
Then I always use quick detailer liquid. Its zero protection, but the best shine. I use it every wash. With a diaper.
Ill see if I can find that link.
Edit:
www.griotsgarage.com/
If i had a 2015 benz... I drive a nissan. Probably should buy turtle wax.