I'm probably alone on this....

If you try to fire the cannon as soon as the cool down time is done you will not be able to keep enough elves in jars. However, if you only log in once every 4-6 hours you will still get all the elves but by not firing the cannon as often you will always have enough elves. But this comes with a down side. What I'm seeing from the forum is that even though we don't have enough elves to fire every 2.5 hours, the people who are logging in more are still way ahead of those that have a large surplus of elves. Mainly because we've cashed in all our elves by firing them already and because we are able to clear the cannon and hatch more often which really adds up. So I'm fine with not having enough elves to fire the cannon every 2.5 hours. I only need 133 bells now to get the island.