To present a scientific subject in an attractive and stimulating manner is an artistic task, similar to that of a novelist or even a dramatic writer. The same holds for writing textbooks.– Max Born
When a graduate student come to me with the big news that its abstract has been selected for an oral presentation, my first reaction is a big congratulations and the second is to already set a deadline for a first version of the talk. Because of the abstract, you already know the content, what needs to be presented. But crafting an effective 7, 8 or 10 minutes presentation is a complete new game.
No time to loose yourself in complex explanations, each figures should be either almost self explanatory (the audience should get the gist of it in a few seconds – the brain cannot try to understand what the figure is about and listen to you at the same time) or if a figure is complex it should be the corner stone of your presentation because you will spent easily over 90+ seconds only on that figure (and you cannot have more than a 1 or 2 of these figures). Forget tables with many tens of numbers, everyone’s brain will simply shutdown and that is even assuming that they can read that table from the back of the room. Usually, there are only a few key numbers that you really needs to present. Keep your mountain of data for the publication!
In fact, even before opening your PPT, Keynote , Beamer or Prezi software, you should have spent time on: 1) your story line, taking into allowed time, audience, … and 2) visual crafting (figures, tables, …). See also Do’s and Don’t of Scientific Presentation.
One thing you will quickly notice is that the shorter the presentation the higher the ratio prep. time/pres. time. I could easily take half a day to a full day to work on a one hour seminar-type presentation (excluding any rehearsing) but will easily spent the same amount of time on a 10-15 minutes talk. That becomes large very quickly 😉
Peoples would tell me, by now you can do this in a few minutes right, you already have everything you need. Well, I have indeed done this for many years and these preparation times are pretty much the rule of thumb that I am using for planning these tasks in my agenda nowadays: 1 hours presentation -> 1 day of work and 10 min -> half a day. Even if the topics is very similar to a previous presentation, it does takes more than a few minutes in-between two other jobs and will take a few hours to prepare. I am not saying that you can’t do it very quickly but it would usually show.