Abstract Reduced quasilinear and nonlinear (gradient-driven) models with scale separations, commonly used to interpret experiments forecast turbulent transport levels in magnetised plasmas, are tested against without separations (flux-driven). Two distinct regimes of turbulence—either above threshold or near marginal stability—are investigated Boltzmann electrons. The success reduced hinges particular on the reproduction fluxes. Good agreement between is found threshold, whilst significantly underpredict fluxes marginality, overlooking mesoscale flow organisation turbulence self-advection. Constructive prescriptions whereby improve discussed.