You know...it’s funny how an old park operator tried to do that very thing from 1955-2000 ish...Yeah. I think every year should have at least one big ticket item opening at some park (E-ticket ride, new land, etc.) and then at least something smaller at another park (could be new show or entertainment or a smaller C-ticket). Have that every year and you'd basically never have people deferring trips waiting for something to open because there would always be something new. And that's how you'd make those every 3 or 4 years people into every year or 2 people.
If only I could remember the name of it
If you do one add on average every 3 years to a park...that very plan comes to fruition and the parks always feel refreshed