I ran a search before posting as I thought this has probably been covered in depth before. But seems not.
I honestly don't know if IBU or not, in fact this isn't really an AIBU, I just wanted to see what other people's experience is, really.
When DCs (particularly very small DCs) are poor sleepers, I appreciate that you'd want to avoid making any kind of noise that could disturb them. I recently visited friends which involved an overnight stay and it was made clear that the loo must not be flushed between certain times. I didn't think too much of it as my sister had a similar rule when my niece was small, but this was the first time I'd actually stayed overnight anywhere and had to use a loo previously used by several other people and not flushed and it left me feeling a bit boaky.
I concluded that I'd rather just gip a bit than be responsible for setting off a pair of screaming children, but it was really rather unpleasant.
It got me wondering what others did/do in these circs? Is having DCs that are a nightmare to settle so all-encompassing that something as trivial as expecting your guests to pee on a pile of other people's waste really is the last of your worries? I can imagine that it really could be, and if so fair enough. If there's just the two of you and you're used to this rule, I can see why you wouldn't want to make exception for when guests visit. But my Mum thinks that even easily disturbed DCs can and should get used to sleeping through a toilet flush. Should they?