I normally don't do it too much, unless it's one of those threads that you know is going to be locked because somebody asks a question and you provide them with an answer. You know, those threads where you direct them to another part of the website because they post in the wrong forum or something? Yeah, those are about the only times I don't come back to a thread.
I always come back to threads I've posted in, mainly because I look and see if someone replies to my post or if there's another interesting post I feel like I need to respond to.