Vallejo model air has a very strong pigment base and you get Lots of coverage from 1 17ml bottle.
I usually reckon on getting at least 3 1/32 aircraft exteriors from one bottle of paint and you should watch and join in with my build of HK's new 1/32 Lancaster. This is a huge kit size wise and also surface wise. This will give you a good impression of just how far a bottle of Vallejo goes.
I would advise you to get a bottle and some white plastic spoons and try yourself.
Model air goes through my airbrush (H&S Evolution Silverline) at 18psi (+\-) with either 0.2 and 0.4mm nozzles direct from the bottle with no added thinning. You will get quite a few 1/72 models out of Vallejo bottles.
Weather permitting today, I will be posting finished photos of the J7W1 Shinden which, with a couple of exceptions, has been done with Vallejo Model air.... And there is still plenty in the bottles!