An extract from the September NSA Speaker Magazine, states that there are four noteworthy facets of a Lightning Talk (named Pecha Kucha in this article).
1. It makes the presenter concentrate on essential information: What do your listeners absolutely need to know and understand? The format forces you to stay focused on what's really important, with no time for digression. Slides are programmed to change every 15 seconds, so you have to anticipate your next slide and ensure that your narrative is synced to your visual.
2. It forces you to have a storyline., a flow that allows your listeners to quickly and easily grasp their message: Speakers often make the mistake of treating each slide as a separate and discreet date rather than part of a larger story.
3. The benefit of using a presentation format that relies heavily on imagery is two-fold: It gives you the ability to transfer emotion, in addition to information and knowledge. It also puts the focus more squarely on you and what you're saying rather than showing.
4. It supports the mantra of 'practice, practice, practice': You absolutely cannot go on stage 'cold'. With just minutes to effectively convey your message and engage your audience, rehearsal is essential.