Question for the Experienced Body and Paint Guys

I'm no pro, but I'm also not a beginner. I painted multiple engine compartments, and one full car.

Anyway, I'm currently working on painting my '67 Dart the original Copper. This is single stage urethane. I have the hood and trunk lid off the car right now because I cleaned and painted the under side of them.

Does it make any sense to leave them off the car and paint the top side of them separate from the rest of the car?

Input please....