Stick to the 10-minute rule. Cook introduced his first “guest speaker,” the co-founder of Anki, Boris Sofman, at exactly 10 minutes into his presentation. The 10-minute rule is a technique I recommend to every presenter, but I must give credit to the person who inspired it—University of Washington researcher, John Medina. Medina once told me that no matter how engaging you are, your audience will begin to tune out of your conversation after about 10 minutes. That doesn’t mean you can’t reign them back in, but if you drone on and on you will most likely lose their attention.