Most conference talks are forgotten by lunch
Not because the speakers were bad. Because the room, the running order and the format conspired against remembering anything.
Organisers obsess over the line-up and treat everything else as logistics. In practice the format decides more than the speaker does: how long, in what order, with how much space between sessions, in a room of what shape.
These notes come from running and attending a lot of public events, and from noticing that the sessions people quote months later share a small number of traits.
The strongest predictor of whether a talk is remembered is not its content. It is whether the audience had a chance to say anything about it within the following hour.
Sections
Programming is about running order, length and the gaps between. Speakers covers selection and the brief you give them. Audience is about the people in the seats, who are usually treated as a measurement rather than a participant.
Who writes this
People who have organised events and sat through considerably more of them. Nothing here is a theory of communication; it is a list of things that reliably went wrong until we stopped doing them.