Same as Fig. 13, but including additional OB stars from Castro et al. (2018), Bouret et al. (2013), and Hunter et al. (2008b), bringing the total number of OB stars to about ∼800. While our sample is restricted to the SGS in the Wing of the SMC (see Sect. 7), the other samples spread all over the SMC. The only outstanding star that seems to reside in the void region was obviously confused in the catalog by Castro et al. (2018); we added a downward arrow because the observed SED definitely indicates log L/L_⊙ <  5.2. The additional samples also support our conclusions on stellar evolution.