Primeval Force gives 5% elemental penetration, and also Forces of Nature has 6% elemental penetration. If I'm already going for Primeval Force, how should I value also taking FoN if its nearby - is it better to stack penetration, or just a little bit goes a long way and adding more will give diminishing returns?

Does the desirability of getting FoN change if other cluster nodes are also considered (FoN cluster gives less bonus than PF).

Primeval Force gives 5% elemental penetration, and also Forces of Nature has 6% elemental penetration. If I'm already going for Primeval Force, how should I value also taking FoN if its nearby - is it better to stack penetration, or just a little bit goes a long way and adding more will give diminishing returns?

Does the value of getting FoN change if other cluster nodes are also considered (FoN cluster gives less bonus than PF).