Quite unlikely that a fairly big retailer like iHerb would stoop to such a level? ;)
As for digestion, you may be right, however, I wonder if it is necessary for herbs to be absorbed before they can have an effect on the liver/gb? For example, bitters can affect the gb just by tasting it.
I also do take the supplements throughout the week, though some times inconsistently. Perhaps it's the timing of the supplements, or because I take them throughout the week, or perhaps my liver is ready to release stones, but whatever it is, I find I can keep getting stones if I stick to this routine.
As long as you're getting stones out with the flush, you should keep doing them! But if this method works for you too then it would be great to get stones out even in between flushes.