Outflow dynamical timescale corrected for a mean projection angle of 57.3°, t_{dyn, corr}, vs. mass of the launching core, M_core (a) and the visual extinction of the cloud background crossed by the outflow, A_V (b). The dynamical timescale of a given core is evaluated in two ways: as the oldest ejection event (triangles) and as the L_max ∕ΔV_max ratio (squares). Both dynamical timescales are plotted in (a), showing that they are generally consistent within errorbars. A single estimate is used in (b), which corresponds to the oldest ejection event (triangles) when it can be measured and the L_max ∕ΔV_max ratio otherwise (squares). No significant correlation is observed in (a). The anti-correlation between t_dyn and A_V in (b), with α = −0.7 ± 0.1 (magenta line) and a Pearson correlation coefficient of −0.67, is reminiscent of that between L_max and A_V in Fig. 8b.