Take your dumps wherever you like but cover them in sawdust
The answer is that it varies. Lift the lid of the cistern, manually press one of the flush valve top sections (if that’s the setup you have and not the plastic cords) and see how much water drains from the cistern and remove the doubt. The cistern water capacity should be set at 6 litres, the more water comes out then the more punishment it will get rid of. Some buttons are designed to be held down as well.Not a single vote yet, ffs! Nobody knows, do they?!
I grew up with those kind of flush buttons, and also easy google searchHow can you be so sure? This kind of thing destroys me.