Most of the time I don't. I normally use the pop up box to jump from question to question and I'll only read other people's answers if I'm genuinely intrigued by the question and what others have to say. Sometimes, I'll read other people's answers when I get a response to my opinion.
I read others opinions (although I try not to do that before I write my own so it doesn't subconsciously influence what I write) and occasionally up/downvote opinions too. Very rarely reply to opinions that aren't relevant to me.