I can only speak to my experience. I have a 2018 CX-9 with MGM paint. I know Japanese paint is softer and more susceptible to paint damage in general (compared to German paint), so I had PPF applied to the bumper, mirror caps, parts of the front fenders and part of the hood. The partial coverage was a mistake because the rest of the hood is unprotected. Also, the seam/edge of the PPF is visible.
For the first year of its life, the car was driven on highways pretty frequently. During that time, I started to notice some tiny chips on the unprotected part of the hood. I thought it may have been a paint problem. Life happened and we moved to an area where the car rarely sees a highway. As far as I can tell, since moving to this new area, there are no new chips on the unprotected areas. This leads me to believe that the main reason I have these chips in the first place is because I was traveling on high-speed, heavy traffic roadways.
IMO, if you'll be driving on highways, or if you find yourself behind trucks/semis/cars with no mudflaps often, get full PPF on the front clip of the car and you'll be good to go.