Both me and Lillian have had several flushes with no stones.
I personally know over 10 people who came to the point that no stone come's out.
If you read all messages posted in this forum, you will read at least 10 stories of people who finally came to the point of getting 0 stones out.
If you have a no-stones flush this year ... it still doesn't mean that next year you will have clean liver. Liver that have been damaged by stress/chemicals/... may continue producing stones for a long time.