While not presenting content to guests, swooping in to fix issues, or sprinting to a different place in the building to do the above, I was preparing for the upcoming demos.
My team rarely had free time, as any downtime was spent loading content onto fresh devices, updating devices, or following up with the various content / production teams on events to figure out what equipment we would need to cover it.
One of my core responsibilities during downtime was to provide feedback to the internal design teams on user experiences. As we were the team with the most hands on experience, our feedback helped drive design iteration, as well as polish from bug reports.