I recently came across the theorem of corresponding states, which states that all gases exhibit the same compressibility factor, under same reduced pressure and temperature (and also the critical compressibility factor). Thus:
$$Z=f(P_r,T_r,Zc)$$
where
$$Z=\frac{PV}{RT}$$
$$P_r=\frac{P}{P_c}$$ $$T_r=\frac{T}{T_c}$$
My question is, what are the limitations of this theorem? Can I consider it as an absolute truth, or is it just like any other gas law, being valid only within certain ranges and for certain acccuracies?