Sound stage

What is the perfect sound stage when listening to 2 channel music? Does it vary from rock to jazz to classical? Should voices always be dead center no matter what type of music you are listening to? Should it be contained between the speakers or out side the speakers as well? Where does stereo separation between the speakers fit in? Should it be layered floor to sealing? Do you adjust your speaker toe in depending on what type of music your listening to? How do you know when its right? I have achieved all the above but never all at the same time.
Thanks Pete