If I would (coulda, woulda, shoulda) have bought this in March at $9 a share, I would now have a 100% gain on the stock price and would be earning a cash dividend of over 20%.
Buffet recently said that if he was working with a smaller amount of money (less than $100 million) he could produce annual returns of 50%. That would mean he was doubling his money every 18 months.
I don't think this is theoretical. He does have a personal investment account seperate from Berkshire that isn't public so he is probably talking from his real world experience.