The spatio-temporally varying turbulent energy cascade dynamics in forced homogeneous/periodic turbulence is investigated with direct numerical simulations (DNS) and Helmholtz decompositions. The local in space and time cascade dynamics vastly differs from its spatio-temporal average manifestation. At scales larger than the Taylor scale, the solenoidal interscale transfer at most locations at most times increases or decreases the energy at the given scale in the frame moving with larger scales, i.e. Lagrangian transport. The solenoidal interscale transfer derives from the non-local in space vortex stretching/compression and tilting effects of its spatial vicinity. The irrotational cascade dynamics reduces to an exact balance between irrotational transport, irrotational interscale transfer and pressure-velocity. The typical fluctuations of these processes vastly exceed their spatio-temporal average values and the typical dissipation fluctuations. At scales below the Taylor scale, viscous effects increase in importance in the solenoidal dynamics. At the Kolmogorov scale solenoidal interscale transfer, Lagrangian transport and viscous effects are all important. In regions of low and moderate small-scale energy, and to a somewhat lesser extent in regions of high small-scale energy, there is rarely a local balance between interscale transfer and viscous effects. Lagrangian transport acts as a non-local in time and space link between interscale transfer and viscous effects. The spatially-averaged manifestation of the local cascade dynamics is an unsteady and approximately unidirectional energy cascade, which can be approximated with a hypothesis connecting the present interscale transfer with the future dissipation. The hypothesis can be used to develop non-equilibrium corrections to the low-pass filtered dynamics and second-order structure function scaling consistent with DNSs. We use the phenomenology of a time-lagged energy cascade to motivate a new redistributive dissipation scaling. The non-equilibrium dissipation scaling typically reduces to the redistributive dissipation scaling at low and moderate Reynolds numbers.