I doubt that anyone can be 100% gall bladder/liver stone free. Even if you manage to get yourself stone free with several liver flushes, this will only be temporary condition and it won't be long before your body begins to produce new stones. Some say that the purpose of the body in producing stones is a natural mandatory/essential state that is partly related to the body's attempt to maintain a balanced PH. If no stones were ever produced, you would become a walking vat of acid and dissolve in no time. Weight loss, use of oral contraceptives, prescription medications, etc., are known to rapidly increase the production of new stones.
IMHO, the goal should be to minimize stone formation. This should be the ultimate goal of maintenance flushes as well. As your biochemistry changes for the better through flushes and a healthier lifestyle(included healthier diet and daily exercise), stone formation should be begin to decline automatically. The problem in most cases is when old stones through poor diet and lifestyle become calcified. You can also experiment with things such as castor oil packs which are alleged to reduce the formation of new gall stones.
Although everyone is different, I would caution against doing Liver Flushes every week. A Liver Flush does cause a temporary biochemical imbalance that the body needs to recover from. Doing flushes too soon can interfere with this process and likely create a greater imbalance. It is important to respect your body's need to recover from the flush. IMHO, recovery/healing time from a Liver Flush is just as important as the actual flush itself.