I think one thing to consider on terrain is a person's physical fitness. An 11 mile hike may be a bit wearisome to most of us, it is dang near impossible for others. This being the case, the numbers can be very misleading. The same goes for difficulty. A seasoned veteran could view a 4 difficult as probably fairly easy or danged hard if it truly was a 4.
Now you have got me thinking wowieann. I'm going to try to get 1000 find for 2015. It is November 30th and I am sitting at 806 finds right now. That is only 6 caches a day and I am going to at least 2 series event in December.