A deck for a 5 hr meeting?

After my presentation in Barcelona last night, one of the audience members came up to me and asked whether for 5-hour presentations, you should take a different approach from the one that I had been advocating for the 20 minute investor pitch. Two answers:

1. Break up your 5-hour presentation in blocks of high-energy and well-designed 20 minute pitches and discussion sessions.
2. But better still: cut that 5 hours. Give people the opportunity to read things beforehand and just do a discussion rather than going through details for 5 hours. Obviously this might require a culture change in your organisation if people usually do not do their pre-meeting homework.