My experience is that most people don't go for US. Several years ago I was here daily and I can only remember Fernando who had a full gallbladder with stones and flushing helped him but I don't think he ever got rid off them but was able to live with it.
Telman did US as far as I remember and he might have an answer.
My gallstone is too big to come out and I did US for several years. The size changed every year it went from 2.4cm to 2.8cm and some times it was smaller but they said the US could not be that precise, it might have been
the position of the stone. Actually the last time (2008) it was 3.1cm and then I stopped going for US.
This is a link for information that is published under cleanses at the top of the page. May be you can find some info under the liverflush survey (sorry I have never read it).