The shelf life of presentation slides can be months or even years as people re-use slides for new presentations. While we are usually good in updating numbers (it is immediately apparent that last quarter's sales figures are no longer the latest), other content can just sit there gathering dust for a long time.
An example of stale slide material would be using the video Gangnam Style as evidence that music hits are now created online rather than in traditional media. I remember startups still using the amazing growth of MySpace as an example of the social networks long after facebook took over its leading position. (I am writing this post in June 2015)
In the world of technology presentations, things get recycled a lot. Someone saw a presentation somewhere and used it and gave someone else an idea who used it. Very soon after the case example will become an overused cliche, and you can hear your audience's "sigh" when they realise they have to go through it again. It is almost an insult that you considered them that misinformed.
Check two things before re-using that case example:
- Is it still correct? If something used to grow fast and the data is from 6 months ago, chances are that things are different. And - especially on the internets - things can change dramatically in no time
- Is it still interesting? As habits go mainstream, people might not need facts to be convinced of something that is considered to have become part of everyday life. People spend a lot of time staring at their mobile phones, no need for facts here, just look around you.
Case examples are usually interesting if they:
- Are really new
- Are based on data that only you have access to (and are willing to share with the world)
- Make a comparison that nobody before you have thought of
Keep it fresh, keep it original, and make sure you really need that case example to get your audience to do what you want them to do. Giving a lecture about interesting industry trends using stale case examples will not get you very far.
P.S. Gangnam style has almost 2.5b views now, that is pretty amazing. Someone must have the stats somewhere that shows that most of those views were done on mobile devices.