But I thought it doesn't matter how good it is, mixing paint over 2 seperate times will ALWAYS going be a little bit different.
Therefore, if you were to spray your door, they'd blend it to your front fender and rear quarter.
Because if you don't, under different sort of light, you will be able to see the contrast between your front fender (one colour), door (one colour), rear quarter (one colour).
Although sometimes people can never tell, but since you know it's there, you will be able to see it everytime