I think it is different now with the internet. A witness can look up their interview and read exactly what it is that they said at the time. I don't know a lot about witness practice, but do they practice with their witness before they go on the stand? I mean in particular this Charles C, will the state practice with him?
BBM...no more so than the defense will "practice" with their witnesses. That is just how the game is played. Neither side wants to be surprised at an answer to a question posed by the respective council.
Doesn't mean the witness will be persuaded to change an answer, but follow up questions or preemptive questions may need to be addressed to clarify a known answer.