Dihedral Angles Chi Plots.

Usually Dihedral angle Chi Plots are explored for side chain conformations. Max possible side chain angle values are up to Chi 5. My question is that why UCLA-Procheck generates only Chi1-Chi-2 plots. Why not Chi2-Chi3 and so on. Is that is not significant to calculate or due to huge possible combinations defining sterically favorable regions is tough. Is there any tool or online interface which interpret other Chi plots also?