My mom has two sisters and a brother. Growing up we'd always have household Christmas and then everybody would meet up at my grandparents' house for family Christmas. Well, that's how it worked for my mom's family and her sisters' families. My uncle's family would have their household Christmas at and during family Christmas. So my brothers, all but two of my cousins, and I would open one present from our grandparents while two of my cousins would open their grandma/pa present plus all the presents from their parents plus all the presents from "Santa." It annoyed the heck out of me, not because they got so many gifts, but because it was so time consuming and, frankly, showy.
Oh, this happened in my family once. One branch of the family was out of town over Christmas, so our extended family Christmas was also their "get gifts from their branch" Christmas. Awkward all around. Knowing there would be gifts given to some
people, gifts were bought for all, including me and my parents... who hadn't been told about the change. So we received more substantial gifts than usual, but had nothing to give in return. Not the worst situation, but that kind of thing drives my mom crazy, and it was mildly uncomfortable. Plus, all the kids had so many presents that opening them took forever--the good-sized living room was so full of gifts "around" the tree you could hardly get to some of the chairs. Fortunately, this was apparently a one-off, not the new tradition.