Do the current dates first need ranking/grouping if you are looking to add more. There are some that involved other people/strangers mid way through the list then just naked in the tracks so could be in the middle of nowhere later in the list.
Kind of feels like ranking them then grouping them could be quite beneficial here.
Introductory, a, b,c ,1,
Easy public 2,3,4,11
Medium public, 5,6,7,18,19,22, botel hallway, balcony
Hard public, 8,9 ATM, delivery lockers
Extreme (including others) 10, 12,13,14,15,17,20
Extreme (venues) 16,21 sports venue
Then when you want to add to them you know which category to add them too. And you can see which ones ( the original idea behind that post for in to the increased challenge categories)