"I don't know. I just don't know."
Seriously, the writers on DS probably had distinctive styles with stock phrases to use. I know that when I do creative writing, I tend to use similar words and sentences, though after I look over a story or script (something the writers on DS could hardly afford to do considering the time limits they had), I try to avoid repetition.
Count how many times they say, "I don't understand". or they answer a question with a question. Willie talks of a little girl on the estate. Barn - I don't know how many times asks, "A little girl???"
That's nothing compared to all the times we saw actors looking into the Teleprompters! We'd all end up as "friends of Bill W.".
The secret of the Naga lives on...