What is 3 Days?
3 days is the proper exaggeration for any amount of time. Even if the real time is reasonably more then 3 days, 3 days is still considered reasonable.
Andrew: It'll take him 3 days to walk to work. Let's drive by and mock him while throwing snowballs at him.
Bob: It'll take him like 3 days to read that book. It's huge.