For example, House Tully rose to prominence around 300 years before current events, call that 6-10 generations, I would expect to see a lot more Tullys about.
House Stark is 8000 years old, I would expect there would be hundreds of Starks.
For example, House Tully rose to prominence around 300 years before current events, call that 6-10 generations, I would expect to see a lot more Tullys about.
House Stark is 8000 years old, I would expect there would be hundreds of Starks.
There are several houses with cadet branches. The Lannisters have several that we know of, and the Baratheons have a couple as well. As for the others, we don't know for sure but here are some explanations.
The cadet branch may have just changed their name. For instance, House Karstark is an ancient offshoot of House Stark founded by a Karlon Stark who has given his own holdings as reward for his service to the Starks of the main branch. Karlon's Hold became Karhold and the Karhold Starks eventually became the Karstarks.
The cousins may have just died out. In order to not fragment a House's holdings, only the eldest inherits the ancestral lands. The rest need to find their own way in the world. Lucky ones might be given lands of their own, if their house is rich enough. Others have to marry into another house. Some relinquish their family names and become Maesters. Northerners are known to join the Night's Watch. The rest have to find employment in the service of another Lord, or even a mercenary army. The famous mercenary company The Second Sons is exactly what it says.
Westeros is a very violent place. Warfare is constant. In the 300 years of Targaryen rule there have been at least two campaigns of conquest, two civil wars, several uprisings and rebellions, and countless other violent disputes between houses. Nobles of Westeros are expected to take part in these wars, and the result is that many of them get killed. Whole noble houses have been known to go extinct.