Evolution of (a) E_div/E and (b) |E_mix|/E_J, s and (c) θ_J for different NLFF models, using the empirical error matrix W_HMI, and based on differently preprocessed input data (including smoothing: violet symbols; omitting smoothing: blue symbols), and with different weighting of the volume-integrated divergence (w_d = 1: bullets; w_d = 2: squares); (d) corresponding time evolution of |H_J|/|H_𝒱|. The horizontal dashed line in (a) indicates the nominal threshold of E_div/E = 0.08, an upper limit for the accepted solenoidality of the input magnetic field. The horizontal dashed line in (b) indicates a suggested upper limit for the acceptable non-solenoidal error to the free magnetic energy (|E_mix|/E_J, s = 0.35). Vertical bars as in Fig. 1.