I personally find challenge caches pretty crap. Groundspeak tried to get people interested by having challenges (or whatever they were called) as a separate item on your profile. No-one could be bothered with them so they pulled that after a year and now they allow “unknown” and “traditional” (?) caches to have stipulations on them. The whole idea of the game is to find a box and sign your name. I can now for instance find a box, sign the log, and then find that it doesn’t count because you haven’t got X number of DNF’s (or whatever the challenge is). Makes no sense.