On the basis of theoretical analysis and numerical experiments, we study the efficiency of the endochronic theory of plasticity with regular kernel and isotropically kinematic law of hardening for the description of block loading. It is shown that the theory adequately predicts the kinetics of the stress-strain state in the case of strain-controlled loading. In the case of asymmetric stress-controlled loading, the model qualitatively predicts only the nonstationary stage of the process of cyclic creep of the material. To describe this effect more accurately, we propose a simple model of plasticity taking into account the anisotropy of cyclic properties of the material induced by the asymmetry of loading cycles.