Several years ago, I realized that talking in front of large-ish groups of people that I wasn’t on a first-name basis with was going to be an expectation of my job. I had always been fearful of public speaking, and crowds in general throw me off. So, I did what any good glossophobe would do - I jumped into the deep end of the pool and
100% with you on 1 to n-1 being a slow grind. We often assume public speaking is a natural talent, but as you note the best speakers are often also the best preparers. When you are well prepared you can focus on delivery and engaging the audience because the content flows more naturally.