Instructions were clear. I could listen to audio books as I shelved as long as it didn't interfere with my work. The other shelvers worked just as hard as I did, which was reassuring.
What I wish was different
A slightly longer break, or shorter, staggered breaks, would have been nice. At the end of the day, after being on my feet for hours and walking up an average of 10 flights of stairs, I was physically exhausted and in some pain despite being in decent shape. Longer or staggered breaks would have helped that.
Wear comfortable shoes. I know the event--Congress--is very fancy and you need to dress respectably, but wear comfortable shoes. If you wear heels or dress shoes you won't last the day.