I think some people get bored if nothing changes after 3-4 of them. I watch my housemate. He did 5 and stopped...he got bored or distracted.
it wasn't until I read the Liver Flush Forum survey and saw how many people were doing that my eyes were opened to the necessity of doing as many as needed.......
my officemate knows a bunch of teenagers who did them and they had tons of yuck come out and they had to do a bunch of them. We don't realize how sick our environment really is.......