I strongly believe that churches should be in the business of facilitating watershed moments. However, the reality is, not everyone who attend a church organized activity will experience a watershed moment. Therefore our goal and prayer should not be for hoards of people to come to an event but it should be that God will bring those who need to experience watershed moments to a church event. The church in turn should not look at the numbers as point of evaluation on a program. It can be misleading to say that a program is successful if the measure is only in the number of attendees.
That said, invoking the work of the holy spirit is essential without whom the desired outcome will not come to fruition. A program can be successful in spiritual sense only if it is orchestrated by the Lord himself.