As it says really. I don't - because it's just a wee, and I don't watch the noise of the flush to wake everyone up.
However, we've recently had a new bathroom suite. DH says that leaving it will damage the loo since urine is corrosive and will lead to brown staining. I said I thought the staining (which we don't have, for the avoidance of doubt!) was limescale etc not wee damage and I think surely he's talking rubbish - it's a bit of wee hitting the water in there anyway for at most what, about six hours? (I don't pee neat ammonia FTAOD.)