>>527784419
I took that as zenkais (somehow) connecting Zamasu's soul with Goku's body better, since Black specifically says that this is the "true nature of saiyans", so if he took, say, Hit's body, it wouldn't work like that.

>It's probably why you never see SS Black again too, his divine soul is finally 100% in control of Goku's body and thus reaches the divine version of the form, Rose
SSR is his version of SSB in the manga, so he just had no reason to use SS since it's a weaker form.