Well a normal Pantheon based on an improvement makes either two or three per city. I don't particularly care for a hard cap like 30 because the ever-increasing faith yield of Wisdom in the late game is one of the main reasons to pick it (like Commerce or Ancestors). I guess the question to be asked is whether its early-game advantages render it needless to have the late-game advantage for the Pantheon. That is - God of Sun has the same static bonus either early on or later, but this one improves with time - one would therefore suppose that if it is so much stronger later on, then it's early-game impact is weaker. I think God of War is the best and most balanced example of this, as it gives crazy faith and in increasing numbers at all stages of the game, but otherwise no extra yields at all.