It is argued that extended, reducible, and generalized supersymmetry (SUSY) are common in many systems of standard nonrelativistic quantum mechanics. For example, it is proved that a well-studied quantum mechanical system of a spin-12 particle interacting with constant and homogeneous magnetic field admits the N=4 SUSY and has the internal symmetry so(3,3). Then an approach of energy spectra of a SUSY nature is presented and developed. It is applied to a wide class of systems described by the Schrödinger–Pauli equation admitting N=3, N=4, and N=5 SUSY. Some of these supersymmetries have a very peculiar property—their supercharges are realized without usual fermionic variables. It is shown that for them, the usual extension N=3 to N=4 SUSY is no longer guaranteed.