Live shows are dependent on each person knowing their role and hitting their cues on time. Stage shows such as plays are often a difficult mix of perfect timing. Musicals and opera performances add to that difficulty. While plays do have music, it is not the key component. The musicians in the pit are often idle because much of the performance is spoken between two or more actors. In musicals and operas, the orchestra performs during the majority of the action.
Coordinating all the musicians, singers and stage hands during musicals and operas takes a group of specialists. Each person directing a part of the action must train their performers or workers to hit their cues and keep the show on schedule. It takes a group effort from everyone associated with the performance to get it right when the audience is in the house. Conductors, directors and stage managers drill their teams until they can perform flawlessly when the curtain goes up.