Famous examples of authors who did this are mostly found in the fantasy literature. Tolkien (The Hobbit and The Lord of the Rings) and Martin (A song of Ice and Fire). Especially in the case of Tolkien who is famous for his stacks of notes and border writings. He speaks of lands that are barely treated in his novels, but those who are familiar with his Legendarium (all the gathered work of Tolkien) will know there's a lot more to it than his major novels.
|The entirety of Middle-Earth of which maybe a small part is treated in detail|
As such I do want to show that I place a great deal of care into building up the background of my novel and I do hope other writers will do the same, because I always find it nice to find a sizeable background in the stories I read and write. Without compromising the main story with redundant information of course.