I get this question. Often.
One rule of thumb I often hear is "two minutes per slide." That's BS.
Develop your message first... then your slides
Make sure you're talking about the right things in the right way - that's your message.
Spend enough time to adequately discuss your most important points... rather than trying to rush through everything you could say.
Then pull in only the content that supports your message. Some content may need slides, some won't.
But DON'T start with your last slide deck, change some headers, and move slides around to fit the amount of time you have. It will end up full of "stuff" that won't help your next audience make a decision.
Take as much time as each slide requires
Some slides might need ten seconds to explain. Some might take 10 minutes.
And parts of your presentation may be discussion with no slide at all.
If you're going to show something, you must talk about it
I know that seems obvious. But I often see presenters put up a slide (maybe a graph or a ton of text)... and then talk about something else without referring to or explaining the content on the slide. This leads to audience distraction, confusion, or annoyance.
So if you show it, explain it. Why is this relevant? What does the graph tell us? What's the key take-away? How does the quote support the recommendation?
Manage the amount of content, not the number of slides
It will take less time to cover six charts that are on six separate slides... than the same six charts crammed onto one slide.
The more content on a single slide, the greater the likelihood the audience will:
Get distracted (looking at Chart 4 while you're talking about Chart 2)
Hijack your presentation ("Hey, why is the cost so high in Chart 5?")
Glaze over (too much to process quickly, so they stop listening)
And this is true for more than charts (images, text, data).
You should practice EVERY presentation. Out loud. As many times as you can. Determine how long it takes to deliver and if you will leave enough time for discussion and questions at the end. Figure out what to cut if necessary before you get up in front of the room.
Need coaching on message development and use of impactful content?
Let me know.