I could think at an example.
If you have a character that walks normally but you need it one time to walk like a drunk, instead of having this huge main animation blueprint that keeps track of the drunk animation all the time and other special cases animations, you create this animation override where you change the walk normally, to walk like a drunk, and use this animation override blueprint only that single time in the game when needed.
you don’t even need some variable inside the main animation blueprint to check if he is drunk or not.