I am a salesman. Semi-public speaking and giving presentations is an integral part of the job. I don't show up at a customer and read from a script. My approach is generally extemporaneous. That doesn't mean I do not prepare. While I rarely work from notes or an outline, I use them in preparation. I develop what I want to say, and try to imagine every possible question, concern, or comment from my customer. I learned long ago that BS and bluster hurts my credibility.
I'm not sure how the Trumpster has been successful in business. He seems unprepared and dives into his press conferences looking ready to speak straight off the cuff. It makes him look uninformed, unprepared and he responds to hard questions with the very BS and bluster that I find totally ineffective.
There is little difference in what I try to do and a Presidential presser on the surface. Trump is trying to sell his administration's policies. It is embarrassing when the President shows up and it seems as if he learned the material sitting in the parking lot 15 minutes before the meeting. It takes away from the message and gives his enemies ample ammunition. Obama was overly scripted, often using a TelePrompTer at a press conference. He did keep on message. Trump just wings it. There needs to be a happy medium.