When using social media I make posts related to what is mentioned within my profile. So on my Facebook author page I will only talk about book related content, whether it's my books in particular or books from other authors. I may also mention World Book Day and the like, but never talk off-subject. Twitter is different as I often talk about non-book related subjects but the subjects I talk about are still listed within my profile. It'll be about 75% book related but I'll also talk about anime, movies and art too.
The reason for this blog entry is I've noticed a very odd trend recently. I've been following a lot of famous authors on Twitter and at first it felt amazing to be able to make contact with such people, but I've noticed they won't post a single entry talking about the subject of books. I won't mention their names but a lot of famous authors will rant about politics even to the extent of lecturing their followers as though they are somehow morally better people than their fans. One writer in particular only talks about Donald Trump comparing him to Hitler in a lot of cases.
I'm all for political discussions by the way so if that's what someone wishes to use their Twitter page for then I'm all for that. What I'm referring to is when someone has a page to promote themselves or their work and only rants about politics.
I met an artist who drew beautiful illustrations, mainly of cats, and was giving out her contact cards at a convention. When I saw her Twitter page rather than talk about her art it was just page after page of Donald Trump and Brexit posts.
Personally I think it best to stick to subject.