At a pool party yesterday a man told a story and paused frequently with a prolonged "sooooooo..." This seemed not just to give him time to gather his thoughts, but it also marked his place, alerting others he was not finished. At one point he said, "Soooooooo........." then stopped to take a drink of water before resuming. Nobody jumped in to take over the conversation because he had made it clear there was more to come.
Such things are much more common in real life than in fiction because it can be annoying to read dialogue in which the characters aren't actually saying anything of substance. Yet some authors are quite good at inserting conversation fillers into their stories. One is humorist P.G. Wodehouse, who often has Bertie Wooster using expressions like "What ho!" repeatedly, especially when greeting an old pal.
"What was it doing?" asked Piglet.
"Just lumping along," said Christopher Robin. "I don't think it saw me."
"I saw one once," said Piglet. "At least, I think I did," he said. "Only perhaps it wasn't."
"So did I," said Pooh, wondering what a Heffalump was like.
"You don't often see them," said Christopher Robin carelessly.
"Not now," said Piglet.
"Not at this time of year," said Pooh.
There you have three characters conducting a conversation about something they may know nothing about but nevertheless they want to give the appearance of being on top of things. Sound like any real conversations you've been a party to? That Milne was able to satirize such a conversation so successfully in a book aimed at children is amazing.