More evidence of our mounting inability to concentrate on anything that isn't singing, dancing and twittering in front of us... just a few years ago my rule of thumb was one PowerPoint slide for every five minutes of presentation. At most.
They had to be darn good slides. Charts. Sample screenshots. No stock images or bullet-point-list extravaganzas. But if any of speakers at our conferences had too many slides I'd tell them to condense and cut. People can't concentrate and understand if you're whipping along at breakneck speed.
Recently, though, I've begun to add in more and more slides to my presentations. Perhaps one slide for every 2-3 minutes offline and one for every 60 seconds online. Otherwise you just lose the audience. You fritter away their attention if one slide stays up there too long while you drone on and on.
This Tuesday I did a lengthy speech -- an online tutorial on membership site marketing. It had 45 slides for 75 minutes of talking. I did it live on GoToWebinar, so as I spoke I could see the "audience attention" bar flickering at me. The bar measures involvement, I'm not sure how, but probably seeing if people are surfing other windows or not. It was very educational. Whenever I changed slides, the attention bar would pop up to 83-100% involvement. When I talked for more than about 30 seconds while sitting on one slide, the bar would slowly flicker downwards until it sat at about 50%.
Wow. When I did a recorded version of the same tutorial later that night (GoToWebinar is great for live webinars, but the recording quality isn't fabulous, so I try to re-record in Camtasia for posterity even though it's more work), I cut out some of the slight meanderings and brought the speech in at precisely 61 minutes. So, it's probably better now.
However, for my next tutorial, I'm going to ramp up the slide count and try to get it to one per every 50 seconds. The key, though, is I won't be presenting such densely populated slides. Less content per slide. Just enough to be useful and support the speech itself with examples. And to give that continual "flickering" faster-slideshow-feeling that I think may work best in this environment in the Twitter age we now all live in.