1/3). But you choosing these dig sites is YOUR problem, not the game's... Regardless of the use of basic maths xD
I've also just made a thread about Challenge mode and how lacklustre it is since Custom Challenge is basically Sandbox without the option to change the setting mid-game.
Besides you can choose Carnivore only option when playing in Germany in Custom mode. Only problem is that we can't choose is exempt guest type, etc. Hopefully in future we'll get a complete overhaul on gameplay features that have/haven't been added to Challenge Mode as a whole.
It is the game's problem still. It is not just the dig sites, the dinosaur species' popularity has to be considered as well. Almost every well-known species are discovered in Morrison Formation and Hell Creek Formation. With Dryosaurus and Dracorex being a one-star and two-star attraction respectively, the others' popularity rating range from three to five stars. The popularity rating of the Shonisaurus and Archelon are two and three stars respectively.
Of the Custom Challenge mode, I only did the Isla Sorna one to re-enact
Jurassic Park: Operation Genesis' exercise "The Lost World" that is to turn a Site B into a park. Afterwards, I did not play any of the Custom Challenges.
Another difference between Custom Challenge and Sandbox is the genetic modifications. In Sandbox, you can optimize a dinosaur species.
"Carnivores Only" option in Custom Challenge only narrow down to just dinosaurs. As a matter of fact, carnivores not only limited to dinosaurs, but also include plesiosaurs, pliosaurs, and mosasaurs. Despite being labeled piscivores, all the spinosaurs are still confirmed carnivores. One thing that has not been confirmed is whether pterosaurs (except Jelopterus) attack humans for food or for territory.
I finished the DFW Jurassic difficulty challenges along with the ones based on all the
Jurassic Park films and
Jurassic World: Fallen Kingdom without expecting anything
.