Often, detail can be good. Big-picture pitches are vague and generic, and sometimes even insulting to an intelligent audience. Diving in deep in selected aspects of your story shows that you know what you are talking about, and often, the big innovation might be coming from something very specific.
This is detail to adds to, builds on, one story line.
Details that distract from the main story confuse. Going off on a tangent, getting bogged down, are not going to help to convince an audience that comes in cold and which has barely had the time to get used to your funny sounding English accent.
Leave the side tracks for later (if at all), wait for the key idea to sink in.
