The ideal presentation length is...

... 1 page long. It's not always possible to reach this ideal, but shorter is always better than longer. Nothing wrong with having a fat appendix, into which you can put all your backup analysis, and those charts you worked so long on but don't quite fit the storyline. But the actual presentation should be short - 1 page if possible.

Why? Some reasons that came up in yesterday's workshop:

• If you're only preparing a few pages, you can spend the time to make sure that each one is perfect.
• A short presentation reduces the probability that your audience will be reading ahead on page 17, while you're still presenting page 5.
• No-one has ever complained that "gee, that presentation was too short - I wish it were longer."