By adapting to the audience, the speaker can meet audience expectations they didn't know they had, until you met them with your presentation or briefing. As you progress through the ranks you will be required to deliver information more and more, and those in command have limited time - you're not the only person they are listening to, make the most of it. Part of the planning you do should include audience analysis. The University of Pittsburgh have captured the essential preparatory elements to delivering a quality product that achieves your objectives. For example, get your delivery and audience pitch right the first time by considering the ranks present, who are the decision makers and why your information is important to them. The key is to understand and engage with the audience so that you can maintain audience interest and at the same time meet the intended objectives of your presentation or briefing.