Say one can do 1,000 per/hr. So you have 4 of them next to one another 4 x1,000=4,000.
In your case have paralell trails?
Several years ago the crowd waiting was getting edgy, grumbling, I stood on-high asked them for their attention and explained how I had been hearing complaints from people about Other haunts rushing them through, ex cetra and it does take a certain amount of "Time" to do whatever you are trying to accomplish and you are dealing with "People" not guppies in a bucket.
Some will come back again even though the show was not as good as they thought it should be (for the $) Some will return hoping this season it will be better.
Of course some will only give you one chance to do them right.
I have never come close to 20,000 people in one year and I'm open almost every night, often a one-man show (guess who the "man" is?)
My patrons do enjoy or suffer-through a rather different show here geared to Them as far as the sheer amount of attention if nothing else.
After being open 23 years I do have a customer base and a positive reputation, which saves on spending for mere advertising, since my patrons do that for me.
Ravens Grin Inn---"Bring Your Friends, Send your enemies!"