There is one golden number for how many slides should be in any given presentation. The presentation could be a pitch, a conference talk, or an introduction of your company. The answer is simple. The golden number is equal to the slides that keep you from going over time.
The 10-minute presentation is by far the most common. Within this amount of time, a lot needs accomplishing. Believing a particular number of slides will somehow satisfy time and content is a myth. Moreover, a belief that 5, 7 or 8 slides is best will lead thinking away from presentation design and delivery principles.
Designing slides for a 10-minute presentation should start with no limits. Instead, the number of slides should support the presenters' key message. Setting the number of slides for a 10 minute presentation leads to unwanted results. For example, when a presenter gives a maximum number of slides the following tends to occur:
Every single slide is completely full
Too many animations or transitions are on each slide
The presenter speaks unnecessarily fast
Unknowingly, many presenters will compress too much information into a space rather than using the slide to clarify a key point. As a result, the presenter now needs to speak twice as fast. Additionally, presenters will spend an insane amount of time reformulating, resizing and relocating slide content. A better use of time is to focus on reducing and editing out unnecessary details. Thus, as a meeting organizer emphasizing strict time rather than total slide number is far more effective.
As a presenter, keeping to the time signals three memorable qualities:
You are prepared
You know what is important
You respect the time of others
A presentation design and delivery principle is to aim for one point per slide. One point per slide could be, for example, "Obesity continues to rise in younger generations despite increases in regular exercises during the school day." The presenter then decides on a way to make the point credible. This could be using a quotation from a research paper, statistics from a government website, or an image of school children playing.
Inserting more points by way of images or text on the slide would distract. Ideally, any additional detail should only enhance the key point. Information about other countries with the same pattern would strengthen the point.
A great 10-minute presentation will have a core message. The core message is built upon key points. The speaker delivers these key points and uses the slides as support. Keeping to the time is achieved by rehearsing, editing, and rehearsing, no matter the total number of slides.