I think for the most part if people go to one of your off season shows, especially later in the year, they would probably not have the desire to return in October. The urgency would be gone and they'd just want to try somewhere else new. BUT, you've sold them the ticket anyway and you may pick up people who wouldn't come during the season anyway.
I personally think that people generally want their scary stuff around Halloween and that's pretty much it. They will see a movie all year, but the equate haunted houses and hayrides with a Halloween seasonal activity and that's when they are interested. There are always a few die hards who'd go anytime, but not a whole lot of people.