My experiences is that below the age of six, they ALL want to cluster together. Above six it starts to sex-segregate naturally, and around teen years the desire for their own space soars.

But even then they often want congregation, but the ability to retreat. I sometimes think the perfect “large family” house would be tons of tiny bedrooms but lots of common areas. Almost college dorm-like.

Another anectdata - I’ve never met a family with same-sex twins where the twins did NOT live in the same room, even when there was ample space to not do so. I presume the triplet case is even stronger.