I'll hit the worst part of the car with a medium cutting compound and a light cut pad.
I look how quickly the defects are removed.
If 90% of the defects are removed then that product can most likely be used over the entire car.
If only 20-30% of the defects are removed i then step up to a heavy cutting compound and a
wool cutting pad.
If 100% of the defects are removed and the surface is heavily marred then the clear coat must be very soft so ill then step back to a lighter polish. and polishing pad.
I then proceed to do the rest of the car.
Most of my details only get a polish and wax as they dont pay enough, nor care about swirls. So i use a light cutting product
Meguiars #66 and a light cut pad, i've never had a car that this was too strong for. So i dont really have to check.