My understand to the zone system is that it actually divide the entire range of brightness film can capture into different zones. So we spot meter a caucasian's cheek with a spot meter, under that lighting condition, that is reading you should put in zone VI. Because caucasian's face a light. Whereas if I have an asian in the frame, that cheek reading should be in zone IV. If it's an African, it should be in Zone III.
That is just a basic guideline when you do exposure check. Like others point out, it really depends on the film characteristics and the feel you want to get. Nothing better to try shoot and log down the settings for review. I usually don't ask questions before I tried the experiment because I won't retain the information in my mind without trying it myself.