Same as Fig. 5 but assuming a higher galactic Mg yield by 0.15 dex (40%) increase. The additional red dashed line and the red dash-dot line are the half-mass formation timescale determined with the stellar population synthesis method, independent of our chemical evolution constraints, given by de La Rosa et al. (2011) and McDermid et al. (2015), respectively. We note that the red lines are rough estimations (see Sect. 6 below) and may shift horizontally by 1 or 2 dex depending on the amount of gas and dark matter involved in the estimation of M_dyn (see Sect. 2.3), which would not affect our conclusions.