Hi Dog. I think as long as you showed something, it's a success. I don't believe you have to push out hundreds of stones to be successful. As long as you got something out of your system you're good.
I'm a little disappointed with my flush I completed yesterday, but again, I did produce some chaff (and a strange root like looking thing).
I'd have to say that even a flush that didn't produce anything visual is still a good thing. At a minimum, it's cleaning out your gall bladder of old, stale bile.