when good players face off, it's a function of board texture, with slight variation on the margins.
when good players play bad players, the good player would be foolish to play the same strategy used vs the good player. Instead the good player should exploit the bad player by selecting proper counter strategy to the opponents deviation from equilibrium.
so how do we vary c bet %, and also how do we choose which hands to cbet? it depends on how our opponent reacts to the bet initially, and also how the opponent will play future streets.
if we assume a static starting range and assume different strategies from the big blind facing a c bet on the flop, we see different strategies having the highest ev depending on which combination of (fold/call/raise) above is being combated.
think about the different ways your opponent might react to the c bet and come up with a plan vs different opponents. for starters here's a hint:
you can c bet vs the second opponent with lots of value hands, but not many bluffs.
vs one of the other opponents, you can c bet with lots of value hands and lots of bluffs.