If you segment the event, would it be a good idea to do it by a combination of level/region? Because when it's just by region, the camp materials become quickly uninteresting.
And for the structure, I would like an unsegmented event once in a while. Not too often, but once or twice a year would be fun. I really enjoyed doing the Back-to-the-Future event when I was only in Egypt. Discovering bamboo and shale in the last challenge was very stimulating and working my a** off to get that topaze when I only had a 15000 energy reserve was the kind of challenge I enjoy. Right now, I'm doing Easter 2017 just to discover new things like marble and seaweed and lobster and sapphire, just for the pleasure of discovering new things about the game (because the camp materials are really not interesting...). (Of course, you'd have to give something to the Terra players...)
The last unsegmented events are from 2017, so maybe we're due for a new one... 😉
And last but not least, a challenge of strength is not lost on me, but (as I posted elsewhere) I really enjoy brain challenges more. A Einstein-puzzle kind of challenge is super fun. I also enjoy general knowledge questions.