Even if the former haunt was sucky, how many they saw is a good indicator of how receptive an area is. Generally you depending on terrain figure your population is 30 miles out or as little as a 15 minute drive and then your target is 10% of that with the ultimate advertising plan.
The first years can only be done to see what that opening figure is. It might start at what that old haunt was seeing and go up about 30% per year untill it flat lines. If you are only 25,000 with no mans land for 60 miles all the way around you would be favored to see 2500. In that isolated case, seeing even more means having a really spectacular show.
Some haunts thrive on people coming from tremendous distances and have targeted specificly to increase their customer base. Using off season events to sort of train people to drive that far when commanded to.
Some are quite fine with 2500 total, others aren't happy unless they have 25,000 or more. It is also matching the haunt to how many will come expense wise. You could put even the Darkness in a blizzard zone and still only 1000 people will come.
Proper advertising will bring 10 times what a slacker haunt sees the first year. Exactly 10 times.
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