In other words, the screen and bullets would advance without any speaker input, working instead from a timer set during slideshow construction. They can easily get away from the speaker and begin popping up new information before the old information has been covered. Even under the best of circumstances, these features require split second timing from the speaker - very difficult to achieve in unscripted speeches. There are very few good reasons to animate sideshows. Animations within a slide you control yourself are fine, just don't loose control of the sequence of the presentation Tiny Type.
Few things alienate an audience so quickly as having to strain to see a screen.
Make sure that you don't put your listeners through this ordeal. Too Many Slides. Some presenters try to cram too many slides into a speech. This results in one of two problems. Either they go overtime, or they pull slides off the screen faster than the audience can see them.