I personally think it is good to keep doing Liver Flushes every 2-3 weeks until 2 consecutive flushes show maybe less than 10 stones. After that maybe 2 or 3 times a year. I don't think that just a few a year will necessarily ever get them all out. However, there is no way for me to know how many stones you may have.
But maybe you already did the more heavy duty flushing.