We have 24psi from the regulator in the booth after the water trap. We also use a Hi-Flow hose to the gun. I keep the fluid needle fully open to allow as much product as possible. For fan control, usually have full fan. For base and clear we use a 1.4 tip. High-build primer and epoxy is 1.8.Ok...you know me not to be a professional and its been years, uh decades, since I painted cars but....
I remember working out ratios for products. Like 1.5 turns on paint knob for 1 turn on air knob. That, of course, isn't the correct ratio - just an example. Would also work out the correct spray on a white board before hitting the car. Different paints would spray differently.
We worked in an old wood barn with crappy ventilation and inconsistent air QC...but we got it done. On a breezy day, we would have to wet the floor to keep dust out.
Maybe @Bennettjh can chime in if the pros actually do something like this?
All that said, you'll know when it feels right. Definitely go by what the TDS says as well.