I rarely get round to unfollowing people on Steemit. I occasionally do it if they're resteeming a lot of content that I'm not interested in, to the point that it's clogging up my feed. Sometimes I think someone I follow is putting out boring content, but when I look at their blog feed, I invariably find something that interests me, so I continue following them.
A while ago I unfollowed someone because it wasn't just that I disagreed with what he was saying – he was making sweeping statements condemning a wide group of people, but making no effort whatsoever to provide the slightest bit of evidence to back up his views. Usually I'd at least argue the point, but he was doing it in a arrogantly authoritative and pompous way, which really put me off.
With other social media, if someone I know doesn't respond to a friend request, it's usually because their account is inactive and they haven't posted for months. That doesn't bother me. I always refuse Facebook friend requests from people I don't know and/or whom I have no friends or interests in common with. A while ago I accepted a friend request from a neighbour who lives up the road, but whom I've never spoken to. It turned out she was operating a king of social media bingo site that you had to pay her to join, and I got bombarded with stuff like "Winner winner chicken dinner!" In the end I just silenced all notifications from her.