I find stream of consciousness rambling to be extremely irritating. Normally, I'm very much against interrupting, but I have been known to butt in to stream of consciousness speech, saying, "Okay, and what's your point?"
In my experience, that doesn't help. They don't know what their point is yet; they're just gratuitously holding conversational priority, so they can say what it is the instant they figure it out.
Once I detect stream-of-consciousness, I do a warning signal, like a frown or a yawn, then I make a visual cue that I'm exiting the conversation.
The Church of Interruption and Barker conversational style just doesn't work for me. I expect to be able to speak complete thoughts and listen to complete thoughts--thoughts that have a timely conclusion.
