HankB, in making a movie, the scenes are shot individually, which you know. My point is that an actor says a line or two, and then they cut and take a break. They'll shoot dozens of times if necessary to get the lines just right.
That's the difference between a good speaker and an actor. Paul Ryan and Obama, for example, are very good speakers, but can't act (although it could be argued that Obama is acting). Ryan can speak without notes or a teleprompter, if necessary. Obama can't talk to a room of second grade kids without a teleprompter.