Do you imagine yourself having conversations with people in your head?

To prepare for a potential conversation, I often play out the conversation in my head, imagining possible different things the other person might say and how I will respond. Sometimes I'll imagine a conversation I know is never going to happen, just to test out my conversational skills. The problem is that conversations never go as smoothly as you imagine them. In your head you articulate your words flawlessly, but in reality you stumble on them.