The phrase, “You know,” is used for two reasons. One, the speaker is unskilled at the art of public speaking, and consequently, the phrase is used as “filler.”
Two, the speaker wants feedback from the audience to reinforce to him that he is doing a good job of conveying the message intended. But that points to his lack of self-confidence as well.
I never use filler phrases if I can possibly help it. The audience will zone a speaker out for using too many filler words and phrases. In my Belief Therapy class at the Diboll Correctional Center, in Texas, my inmate assistant uses the filler word, “Amen.” And he uses it a lot! So much so in fact, that some of the students have made bets among themselves on how many “amens” my assistant will say in a speech.
I’ve had to talk to him about this, and he has improved, but because he has used this particular filler word for so long, it’s very difficult to rid himself of completely. And the moral of the story is this:
Don’t use filler words in your speeches, nor in your everyday vernacular, because it could become a hard habit to break. And besides that, it just doesn’t sound intelligent.