There are several options for time zone handling, Site's time zone, Date's time, User's time zone, UTC and no time zone conversion. What are the differences between them?
One case would be a television broadcast where everybody in the world would experience simultaneously. Would User's time zone be correct to use? If the broadcaster put 8:00pm while living in New York someone in California would experience this at 5:00pm.
Or, the case, a poetry slam is happening in New York City and anybody who wants to experience it will have to physically be there at 8:00pm meaning it might be happening at 5:00pm in California but that doesn't matter to the person in California. What matters is that they are at the place at 8:00pm in New York so the time shouldn't change no matter where the user is or what time in their timezone the poetry slam is going on.