it took us about 2 hours, because one of those lot had a short attention span and wouldnt stay at their monolith. The level spread I believe is maxed at around 15/16 and its well tough not to outlevel it in the hollows!
With a good team and a "quarterback" (high level player to escort you through the tunnels) id say that 60minutes is not unreasonable for this trial. Well fun story too!
