If you’re giving a 24-minute speech, please do not use the words “and finally” at minute 13.
Now, I know what the speaker was doing. He was presenting the final point of the subject he was discussing. But the audience doesn’t know that. For an audience the words “and finally” are a cue to put down the fork and prepare to clap. If the speech was particularly good, they’re a cue to ready one’s thigh muscles to stand. And if the speech was particularly bad, they’re a hopeful ray of light at the end of a vast tunnel of boredom.
However good a speaker you are, don’t say “and finally” until you mean it.