It’s all about preparation
Winston Churchill once said that for every minute of a speech he would spend one hour preparing. By those calculations a 45 minute presentation would have taken him around six and a half working days to complete. That may be long enough for a seasoned orator like Winston, but for most people I think you need a lot longer. It usually takes me around two weeks to prepare a new talk, pulling 12 hour days. So that’s easily two or even three hours per minute. If you haven’t done the research or put in the hours, it’ll show in the quality of your slides, the quality of your argument and the quality of your delivery. In short, the more time you put into your talk the more polished and professional it will be.
Via Jeff Lindsay.