The question in the title is not a joke. If somebody asks you to give a 30-minute presentation, and you prepare 30 minutes’ worth of remarks, I can more or less guarantee your presentation will not be a success. If you want to get your message across, keep it shorter, much shorter, than the time allotted.

Fine-tune the level of detail in your presentation based on four factors.

1. What is the audience’s attention span? Researchers disagree on the adult attention span. Some say it’s no more than five minutes, and some say it’s as long as 20 minutes. Just keep in mind that there’s a finite time that an adult mind can focus on a topic, and when you exceed 20 minutes, no matter how good your presentation skills, you’ve probably lost most of the audience. If your remarks really need more than 20 minutes, find a way to break your message into parts so you can get one part across then get the audience refocused for the next part.

Attention span is not a fixed quantity, however. It can be extended or reduced by the audience’s interests and by context. You may not be able to do anything about context, but you need to be aware of it. An audience of investment counselors, for example, is likely to have shorter attention spans the day after a stock market crash than the day after a market rise.

2. What is the audience’s stated interest in the subject? Regardless of attention span, audience members will focus on your remarks more easily if they are interested in your subject. A presentation on alien life addressed to science fiction fans can likely be much longer than a presentation on bicycle safety given to residents of an assisted living facility. If you’ve been invited to give the presentation to a particular audience on a particular topic, you can assume a certain level of interest in that topic. But be honest in your assessment and try to research the audience ahead of time so you understand their interests. Make the length of your presentation proportional to the intensity of their presumed interest.

3. How strong are the benefits of your presentation to the audience? If your presentation is to announce a big pay raise to a group of employees, you can probably go on at some length. But if there is no way for you to offer some benefit to the audience for listening, better to keep it rather short.

4. How engaging are you as a speaker? In general, audiences can focus longer on a speaker with charisma than they can on one without. How do you get charisma? There’s a course for that: Executive Presentation Skills®.

My advice is to plan as short a presentation as you can and use whatever time remains for a question and answer session. That way, the audience will determine the length of the presentation and the level of detail they need. If you’ve done your job well, they may give you more time than they allotted, but it’s never a bad thing to exceed the time allotted when the audience asks you to.


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