yes Nerd, that's why the painters have measuring cups and why you buy all the paint you'll need in 1 go - the reducer and hardener don't affect the color if you stay in the ball park, painting in a shop where temp and humidity are fairly controlled takes care of the rest - it should only take 3 sessions max to do everything - 2 in a good booth of reasonable size
you have heard of partial repaints? not hard to paint half a car and have it all match
Bill