Traditional European meat stock (chicken stock, beef stock, etc) is boiled for 6 to 8 hours. Supposedly (according to many answers on this website) there should be absolutely nothing left to extract from the bones and meat after simmering for that time. Yet Chinese white stock is made by boiling (not simmering, but proper boil) bones and meat over one or multiple days.
I have a prepared chicken carcass that I'm planing to turn into a chicken stock. I wanted to boil the leftover bones from making stock for another day to make a white stock, but after some reading it seems to be a waste of time. I might still try it just to experiment.