After eating straight pineapple for three weeks and then on and off with mainly veg, my last flush only produced ¼ cup of very very fine gravel-like soapy grit.
The pineapple dissolves the stones and makes them small enough to pass out regularly in urine unnoticed, which negates the need for so much flushing.
My other previous flushed had around a cup of pea to fava bean sized stones. The last one I had no discomfort, no illness, just very mild - I suspect on account of the copious pineapple, followed by fruit and veg.