Thank you very much. That explains all things I have seen--cities with a whole lot of W/W and the cities w/o any at all.
I have more wishing wells in my city than I would prefer to have for one reason. I often can't get enough daily aiding for the buildings I have that need it. My friends list is at 140 or just below and its people that aid three or more times per week. The short coming is that I'm in a six person guild.
All of my Wishing Wells are the small variety so I've done my best to maximize the space to output ratio. As I get more Special Buildings from events, the number of Small Wishing wells will diminish. In the meantime, they're more productive in my opinion than an unaided Sacred Skywatch or Shrine of Knowledge.