While I am sure that Jeff has seen a lot more Factory Mustang hoods than I, I have not seen one, Mustang or otherwise, exhibiting "the Wave".
I agree with Jim's comments. I had my '57 Ford Retractable sand blasted in the mid-seventies. notice that I said "sand" blasted, not media blasted. That is because "back then", there was no glass bead, walnut shell, soda blasting, etc. being done. The outfit that did it for me asked me to chemically remove as much of the top layer of paint (I had the car repainted in the early 60's, before I started painting myself) that I could, as they were concerned that blasting two layers of enamel might cause warping of the broad areas of sheet metal (even though the sheet metal was of heavier gage at that time. Even after I did that, they said they had to be very careful as the original Factory paint had almost been "rubberized" over time. Bottom line, it turned out fine ; no waves, blow throughs, etc. Back then, as Jim noted in him doing his own, people weren't "rushed".
My only complaint was that for years, and even to a smaller extent even today, almost 45 years later, I was vacuuming and blowing sand out of nooks and crannies that I had done before. Which is why I decided in the late 70's that I would never have another cfar body blasted ; only those parts which could be removed and thoroughly cleaned. Ihave done several cars, and parts of cars since then, and if they had more than just the original Factory paint (which can easily be sanded, primed and painted), I have used Aircraft Stripper ; a little messy, but better than having blasting media appear for years.
Just my personal experiences.
Bob