But to me, outside of the time restraint there is no challenge. The caches are easy enough to find - To me, you may as well be counting as many pebbles on a beach you can in 24 hours or drive down I-95 and write down all the Maine plates you can in a given time. The caches really seem to mean nothing. If you want to get technical, in the case of the alien series, you are actually not finding the original cache nor are you signing the real log book. They have all been replaced by new finders several times over, and not because they needed maintenance, but to save time and claim the numbers. I'm not sure if I could claim them as a find myself. Heck, if all anyone wants is a challenge, come to my house and see how many windows you can wash in a day, we have well over 500 individual panes of glass, and both sides need cleaning.
If you can have fun doing them, I take no issue with that. I'm happy to hunt out the unique and memorable caches, even if it is only one or two for a day.