Curious, I was looking around some in The Collected Works of Alex Elmsley and it was talking about telling them what you are going to do and then doing but telling them only so much as to not reveal the secret of the trick.
There are different schools of thought on this. John Bannon very much advocates just saying what you are doing - even while acknowledging that Eugene Burger calls that style "narrating the adventures of the props in the magician's hands."
If all you talk about is what you are doing, what is the audience going to focus on? Exactly, what you are doing. If they do that, what is the first question that comes to their mind? Yep, "how did you do that?"
Darwin Ortiz talks about "challenge magic" in his book Strong Magic. He uses Slydini as an example (which I disagree with in that Slydini's performances were very much dependent on his personality and his admonishment of his spectators --"you look but you no see" -- was part of the presentation) but I think that the say-do-see patter is a very subtle and unintentional form of challenge magic.
Maybe there are other factors at play (age, experience, performing parlor rather than street, prestige), but I've never had a spectator ask to see or touch anything. I think my rules are the best explanation for that.
A different way of looking at it is to ask this question, "What do you want your spectators to be thinking about when you are performing?" My answer is that I want them to be associating what I'm talking about (be it a personal story, an interesting historical or scientific fact, or just sheer nonesense) and how it relates to what I am doing. When spectators talk to me about my performance, they talk about "the one where you were telling us about..." not "the card trick where the deck disappeared."