One of my client’s recently did research online to learn more about what constitutes a good presentation. I give him credit for his diligence, but he did this research after putting together his own draft which was, perhaps a little too wordy. So the client came to me and said, “I think I gave you too much text. So and so’s book says that there should be no more than five lines of copy on each slide and no more than five words per line. What do you think about that?” Well my answer to him was, yes, that’s a good rule of thumb. But if you have very little content, you had better be a great presenter.” He said he was, and proceeded to cut his copy way way back. It became so abbreviated that it no longer flowed. There would need to be a whole lot of talking going on to fill in for what was not being shown. So, in summary, you can’t always follow books like Presentation Zen as though it was the Bible.
Try and establish a happy medium between over and under explaining. What the presenter is showing and what he’s saying should compliment one another. We don’t want them to read your slides, but we don’t want them to disconnect with what you’re saying because the briefness of your text merely confuses your audience.