Jasmine
Hi
I agree that when stones are no longer coming out is the time to go on a maintenance program e.g. flush once every 6 months or so.
The important thing to remember though, is that if you don't change your diet and eat a lot of high cholesterol foods and cooked de-natured fats (assuming you do) then you will always have stones coming out and would probably need to flush more often. Obviously this is not ideal, although I do know of some people who prefer to keep flushing rather than make lifestyle changes.
Many vegans, like myself (especially those whose diets are high in unrefined oils) seem to find that they have generally fewer stones, which have in my opinion probably been formed before the change in diet.
This is only my opinion and it would be good to hear from other vegans, especially those on raw diets to find out if they have found the same things.
Anyway, good luck and happy cleansing.
Jasmine