Apparently we all should go on doing flushes until hardly no stones come out for two consecutive flushes. Then you can do just one or two per year as a mantainnance.
I did two successful flushes so far and never used epsom salt. I follow the recipe of Mrs Chang the owner of www.sensiblehealth.com. It also works wonderfully.
Apparently stones are form due to stagnant bile in the liver. This is due to harmful foods to the liver such as: White Sugar , white flower, deep fried foods, caffeine, chocolate, among others. Of course that processed food should be heading the list.
Good luck and enjoy the freedom of more stones out!!