I'm going to take the charitable view and assume that what they found was true and reproducible within the artificial scenario they created, but I'm with you — conversation is a dance. It's less about "how much to talk" and more about meeting the other conversationalist(s) energy and vibe, vibrant interaction vs. monologuing, "yes, and"-ing at the right opportunities, not needlessly interrupting just to hear the sound of your voice, etc.