Optimal current setpoints in the form of Maximum torque per ampere (MTPA) and Field Weakening (FW) curves are well-known for three-phase machines. Fivephase machines have more freedom in searching for optimum since the current waveform contains except the first harmonic also the third harmonic, which has a role in torque enhancement and waveform shaping. The problem does not allow for an analytical solution and has to be solved numerically. In this contribution, we analyze the resulting solution and provide guidance for its implementation. Specifically, we show that the optimal operation has MTPA and FW regimes that have an inner structure with multiple sub-regimes. This variety comes from the limits imposed on the maximum of the waveforms of the phase voltage and phase current (peak shaving). A taxonomy of these regimes is provided, and their mutual relations are demonstrated on two exemplary machines. Moreover, we show that commonly used assumptions on the symmetry of the waveforms yield suboptimal results. The theory is validated experimentally on a laboratory prototype of a fivephase PMSM drive of 3 kW.