It takes a minimum of 12 days for the bile salts to replenish themselves. Some of these are manufactured in the liver a fixed rate which can't be changed.
During this 12 day period because the bile salts are low it will increase the chance a forming stones. After this your digestive settle down and you will be able to evaluate you improvements during the 3rd week. With a week of preparation prior to a flush you can see that 4 weeks is an ideal period between flushes.
Also consider that the body goes through its normal cleansing cycles over a month and if the liver is decongesting it requires time to do this.