The same way the Met and other operas can have 3 or even 4 shows run in repertory- their crew runs changeover late at night or in the morning, and everything's designed to be moved on and off stage easily.
The longer the run, the more audience members you can attract. Generally, one cast performs all the shows that season. However, I'm not sure what the deal is this year since they'll have 3 shows running at the same time. Maybe they'll have 2 casts?