Sometimes, busy people need to remind themselves (and us) how busy they are by shaving off the last two seconds of what would otherwise be a pleasant interaction.
At a restaurant yesterday, the maitre d, who is paid to be busy, looked up our name in the reservations book and then said, "over there against the wall," while he pointed. He repeated this approach with at least three other parties.
How much longer to say, "Welcome, we'll be ready for you in just a second. Would you mind waiting over there please?" Amazingly, saying that while smiling takes precisely the same amount of time.
I know you're busy, so I'll keep this short... if you're going to interact, spend a few extra beats to be calm and gracious. It's hard to overstate how much better everyone will feel and how much more productive you'll become as a result.