No.
Though it's always recommended and even I always emphasize on using a panel prep before applying a sealant or coating to maximize the life of wax due to bare bonding between paint and sealant.
But in this method as mentioned above I used meguiars ultimate polish which contains filling agents in it and by using a panel preo I would have loose them giving a lower degree of finish. Secondly this car is for sale purpose so my main motive was just gloss nothing else .
If it would be my personal car I would change
Megs ultimate polish with 3d 520 finishing polish
Use koch chemie panel preparation spray
Apply soft99 fusso coat and top it with collinite on the very next wash