I only have one set of grandparents, my mom’s parents, and they have five children. Of their five children, one has two kids (and five grandkids); one has four kids (and two grandkids); one has two kids; and two are childless. Of the two childless ones, one is in a rest home, and will be for the rest of his life.
My grandparents have divided the estate equally among their children, with nothing to the grands or great-grands. We all kind of have problems with this, but the grandparents can do what they want.
My mom and her sister don’t want anything out of the estate; they’re both pretty well set for life, and so they’d rather the money go to their brothers, who are in situations or stages of life where that money could make an enormous difference. But the grandparents don’t want to “cut them out of the will,” for emotional reasons. So my mom and her sister plan to quitclaim when their parents die, so that their share will go back into the estate. (Yes, all of us kids also will quitclaim.)
My other problem with the way my grandparents have set up their will is that my uncle, who is in a home, still gets a share. But because he is currently supported by the state, the state will take his share to pay for his medical needs. If my grandparents instead would put his share into a special needs trust, the state couldn’t touch it, and he could use that money to buy things that the state won’t: crossword puzzles, sweaters, slippers, etc. But for whatever reason, they don’t want to do that.
But it’s their money. They can do whatever they want with it.
My only other grandparent was my dad’s grandmother, who died when I was a teenager. She left everything to my dad. Only one of her three children still was alive at that time, and she had a bunch of other grandkids besides my dad, but because her estate was relatively small, she just left everything to my dad, to whom she was closest.
To answer the OP, though, as many different kinds of families there are, you could divide the estate a zillion different ways. My maternal grandparents are giving their estate equally to their children; my paternal great-grandmother ignored her children and left her estate to one of her grandkids.