Like a stand-up comedian who makes it sound like he's telling an anecdote (that just happened to come to mind) for the first time, even though he's told it a million times on stage before.
("Acting is acting like you're not acting.")
[Comma 3] https://www.youtube.com/watch?v=hbLiehrC2DQ
In the middle, perhaps lies Steve Jobs:
[Handling Criticism] https://www.youtube.com/watch?v=oeqPrUmVz-o
[iMac announcement] https://www.youtube.com/watch?v=BiWd8ujtK5k
You should not be memorizing your exact lines and intonation, unless you are an excellent actor (Which you aren't, because you are a developer). It's creepy and robotic, and people know you are lying when you are barking words someone else wrote for you, that you don't understand or believe yourself.
Imagine you are a developer who are going to talk about a product you worked on, and you are aware that millions of people[1] are going to watch you present. You're telling me you wouldn't want to do everything in your power to be well-rehearsed? You wouldn't try to do things like learn how to stand still or not stutter?
Like, that is just... I absolutely cannot comprehend that you would prefer to appear unrehearsed to people. Rehearsing is not weird, it is not unusual, and it is not unreasonable. There are soooo many valid complaints to make about Apple and Apple culture, and I just don't think "they over-rehearse their presentations!!1!" even remotely makes the list.
[1] This website claims some 2.7 million people watched the September 2021 event live: https://streamscharts.com/news/apple-event-sep-14-viewership