We had a very good experience with the fuel rod last summer, using it to keep 5 phones charged, we were constantly swapping it out for a fresh one. Epcot, indeed there are fewer places to swap it out, but they are well placed. One is centrally located in Future World in the camera center next to Spaceship Earth, so no matter where you are in Future World, it will only take a minute or two if you need to go swap it out. The other two are in World Showcase. The first one is in Disney Traders, which is the gift shop to the Left as you are entering World Showcase from Future World. The third is in the World Traveler gift shop, by the International Gateway between France and the UK.
These two are spaced close enough together that if you are walking around World Showcase, by the time you run the charge off of one, you will be at the next location to swap it out again.
Animal Kingdom we found a bit more challenging, being that there is only one location there. It is centrally located in Island Mercantile, which makes it relatively easy to get to, however, it would be a lot easier if there were another location or two, perhaps somewhere in Asia, and in Pandora.