Cascade optimization according to the criterion of maximum elemental separation power determined using the separation potential is examined. It is found by means of a computational experiment and comparison with minimization of the total flux that different forms of the potentials, including their dependence on the separation factors, can be used for binary mixtures irrespective of the enrichment at the cascade steps. For multicomponent separation, the choice of separation potential depends on the isotopic mixture and the particulars of the process.