Each pantheon/region will have it's own monsters, spells, magic items, deities, etc. : so the four books (all editions) are more than enough for any one human lifetime.

However, don't see these as rules : the mathematics, and the resultant inhibition of storytelling, are not 'correct'.

Translate these into S&S.
With S&S, the idea is not to be realistic, but symbolic.
It is the story that matters : S&S is not meant for the computer!