Is time the new paper?

I am just reading this accurate blog post on Apollo Ideas: break up bullet point slides into multiple pages that focus on one idea each. Many of my clients object to this technique. "That's too many slides! I only have 25 minutes!" They are choosing the wrong metric; number of slides, kilos of printout, presentation file size, it does not matter. Time is the only relevant factor. When you have 25 minutes to present, you bring slide material that will not exceed 25 minutes. That could mean: 50 slides, 750 gram of handouts, 5 paper flip charts, or a 70MB file.