Script writing
Not all presenters need a script. If the allocated time is two hours and the presenter is an expert, they can talk with little preparation. They will tackle one issue after another and will not run out of time.
Problems start when the presenter has only 10 or 15 minutes to talk. It is challenging to include all aspects of the subject, in the right order, while improvising on the spot.
A carefully crafted script will not only include everything in a logical order while guiding the audience through various emotional states towards the understanding of the problem and acceptance of the proposed solution, but will make the speaker feel confident and prepared.
The scripted sentences can still be natural so that the presenter will not sound like they are reading. There will be a powerful opening line, brief pauses to facilitate understanding, and brief pauses to change the slide which again will give the audience a moment to digest the last statement.