Here is an example of the advantage for post color corrections, I am not very familiar with 3d lighting tools so usually I grab what I have and quickly move on to compositions rather than spending time tweaking with numbers and the complex value of light physics, especially when you are not dealing with animation. Preparing 3d rendered images for offset printing is equally challenging where practical experience is necessary to achieve the intended results during reproductions, the reason is that RGB image is meant for display device which is the spectrum of light while CMYK are pigment ink which require a white surface to reflect colors from. So, it is four colors vs. the rainbow. Knowing the fact that CMYK can never reproduce the kind of colors you see in RGB, we can only improvise, that is if you care enough for a better looking picture.