When I first started cooking, I relied heavily on recipes from trusted cookbooks. Methodically following the instructions, I was able to produce impressive meals.
Slowly, I started to tweak recipes to meet my own preferences, adding a bit more of this, a little less of that.
As my confidence in my judgment improved, I began to change recipes significantly or create dishes just by assembling what seemed like a good mix of ingredients.
In many ways we go through the same cycle as presenters, initially relying heavily on our pre-scripted outlines and notes, and eventually feeling confident enough to draw on the best ingredients (content segments) and assemble them in real-time, tweaking and fine-tuning based on our read of the participant's tastes.
The faster you can move through this progression, the more powerful the learning experiences you can create.