I suspect there are a bunch of different approaches, and different people will find different approaches work for them. Personally I'm not much of a reherser.

I suspect there are a bunch of different approaches, and different people will find different approaches work for them. Personally I'm not much of a reherser. I like to make a point with each slide, and as long as I know the point, I can "freestyle" the actual text. The exception are high-speed sessions, where I have a slide, or two, per sentence. They have to be highly scripted and so I practise them a few times. But, while they're a lot of fun, I don't do them often. For me, prep is much more about what to leave out. It's easier to do a 2 hour session than a 1 hour, and harder still to do 30 mins. Slides mostly help to keep me on track and not get distracted.