Oh, my. What does he define as "too much" preparation?
When I am going to present, I have a stack of material that I have read ahead of time. I use that material to prepare a PowerPoint presentation. While some people try to fit everything they want to say on PowerPoint slides, I don't do that. My slides are just talking points which I use to remember what I want to say, and I do not prepare for a presentation by memorizing what to say. Usually, my presentations go off pretty well.
I do what you do, and I’ve done a lot of them, never felt I was 100% perfect but generally would say I was in the 90s with positive comments. This other guy was trying to memorize word for word, and that’s what gets you into trouble. My powerpoint decks become mnemonic devices for me - as soon as the slide comes up I am reminded of how I want to take the audience through it. Many people resort to just reading their slides, which is very ineffective, and some have said it’s because they’re afraid to be extemporaneous out of fear they will get a word wrong.
The point the professor was making is that Trump is a quick study, asks questions to clarify so new information is assimiliated, and they he is prepared.