<p>A generalized model of a quasi-ideal cascade is presented that allows one to use different values of partial flow cutoffs for individual sections of the cascade. A method for determining a set of parameters that ensure the achievement of the required concentration of the target component in the output flows at a fixed number of stages in each section of the cascade is developed.</p><p>The possibility of optimizing such a cascade by sorting out variants of the length of its sections and values of the mass members of the reference components (actually the cutoffs of partial flows) at given output concentrations of the target component is demonstrated. A comparison of the efficiency of quasi-ideal cascades with different numbers of sections, differing in the choice of the mass number of the reference component, is performed.</p>