My process for crafting a presentation:
I can’t fully form a complex idea without doing both writing and talking. Writing helps me unravel ideas into more coherent groups or buckets, while talking helps me simplify each idea to be the easiest possible way for a person to understand.
Editing then usually involves looking at the presentation as a whole and thinking about order and flow that makes things better, and removing too much repetitiveness. That creates the need for more cycles of writing and then talking.