Speechwriters will still work on the answers for him to use in Q&A sessions, obviously it's not quite the same as a speech where he can give an exact word for word, but generally he'll still know big chunks before hand on a range of anticipated topics, then the skill to doing it live is being able to pivot slightly from the way the question was asked to the answer he wants to give.
Also just realised I spelled "feet" wrong in my previous comment and feel terrible about that.
