Why do so many people get more than one round of BBL?

Hello All, I wanted to put something that's been on my mind out there. I find that many people talk about "round 2" for bbl. Why is that? Is BBL a surgery that doesn't give good results the first time and you have to keep going back? Does anyone know any reviews of people that are just satisfied the ONE time they get BBL? I'm sure there are other reasons why people get round 2 like maybe they were unhappy or they had a child and their body changed again IDK. I guess I'm getting a little discourage because I feel like maybe this procedure has to take place a few times in order for it to be done right? ugh! need some other perspectives on this. Thanks ladies.