Editor's note: Chris Donaldson is creative director at U.K.-based health care consulting firm Kantar Health.

Flying is one the best ways to get a snapshot of how people are using PowerPoint and their approaches to presentations and slide design. Think about it: You get a great spread of people of different ages across different industries who, as soon as the fasten seatbelt sign goes out, fire up their laptops.

We’ve got Mr. Bullet Point in 24D, who is mass-producing slide after slide of black text in tiny Calibri. We’ve got Miss SmartArt in 26B with a satisfied smile on her face as she’s just discovered SmartArt and has created one hell of a flow diagram for which no doubt she will reward herself with a treat when the cabin crew come round. We’ve got Mr. Copyrighted Google Images, with his deck full of technically illegal or stretched images (arguably even more criminal). Then in seats 32A and 32B we have a couple of market researchers on their way to present a proposal to prospective clients. There’s some heated reordering of slides and then the fateful words: “We need to get this down to 20 slides.”

Admit it – it’s something we all do. We’ve either given ourselves or others we’re working with a limit on the number of slides we want see in a PowerPoint deck. I used to bite my lip when clients would speak of an important person in their business who works to the rule of, “I don’t ever want to see more than seven slides.” Now, as design has become more important than number of slides in presentations, I confidently articulate an abbreviated version of what will follow.

As counterintuitive as it may initially seem, putting a limit on the number of slides is one of the worst things you can do when designing a presentation. When we put a limit on the number of slides we expect to see, what we’re actually trying to do in most cases is to limit the amount of data or information we want to see, but there is often little correlation between the two. I’ve seen great presentations of 200 slides, each with a lot of white space, a strong sense of story and an engaging presenter. I’ve also seen poor presentations of seven slides (mostly for important people who insist on it) crammed full of information that have no impact whatsoever.

In many cases, limiting the number of slides is totally counterproductive; you simply encourage people to put more information, more data and more words onto each slide and the result is often a poor presentation where the audience struggles to find the message. If, for example, you had to deliver 30 messages to an audience, it’s likely the presentation will be more impactful on 30 different slides rather than having these messages delivered on 10-15 slides. I’d also argue it would take no more time to present the 30 slides. It is less likely there will be confusion as the audience is less likely to struggle to make sense of each slide. There are probably some puritans out there saying, “No presentation should have 30 messages contained in it.” If this is you, you’ve never been asked to present a global quantitative research study to the pharmaceutical industry!

People simply can’t get the number of slides out of their head when it comes to designing presentations. I have had this conversation or conversations very similar to this about 10 times in the last year:

Me: So I’ve taken the four messages that were put onto one slide and I’ve put them on separate slides.

Them: But we now have four slides, not one.

Me: Correct, but this way those four messages are very clear. One is not competing with the others on the same slide. You’re still delivering those four messages …

Them: But we now have four slides, not one.

Me: It’s clear this way. Your audience are more likely to remember these four points.

Them: But we now have four slides, not one.

Me: What’s the capital of Iceland?

Them: But we now have four slides, not one.

If you really want to take the above argument of limiting slides to the extreme, it is possible to place an entire book such as The Bible on one slide using a ridiculous number of builds. It’s a slightly facetious example, but in essence, if we’re constrained by a number of slides this is often what we are doing, albeit to a lesser degree.

A far more constructive approach to maximizing the chances of a PowerPoint presentation being impactful is to adopt the philosophy made by TED where a limit is put on the time the speaker has to present (18 minutes in TED’s case). Personally, I’d like to see more organizations adopt this approach. I’m not talking about simply setting up a 90-minute meeting and giving someone freedom to present for the duration of the meeting. I’m talking about significantly reducing the time available to present. I would propose a 30-minute limit. A quick look at audience attention-span data would suggest that this is generous, no matter what you’re presenting, and you should be able to get the salient points across within this time frame.

There is no perfect way of ensuring an impactful presentation; there are simply too many aspects that influence it. We can, however, increase the odds of receiving a great presentation by reducing the number of elements that set us up for bad ones, so let’s all agree to end this ridiculous slide number limit that we put on our presentations.