Grad Nites do have an impact on the day guests, as the event has morphed from a true after hour to dawn experience, to what is offered today.
And that is a Ticket that allows the Grad to visit the park that day during normal operating hours, and access to an after hour event that last a few hours after the park closes to those with a regular admission media. So the parks do get busier than normal on a weekday, and closes a bit earlier than normal, especially those held in June, which are busier than the off-season May dates.