Exactly. AKB is so big right now, that most girls are aware that once they have left, they will be never performing in front of 10000s of folks in their lives, or be enjyoing similar success with whatever they are about to do. That is why i will never blame members hesitating to graduate. I know the whole system was meant to base on the "new girls in, finished girls out"-equilibrium, but those are girls having the time of their life. And they probably know that. Obviously, all members like to expose themselves to the public and perform on stages, so why leaving the fun behind then? At least i would think that. Take Kana for example. 2nd gen, almost 8 years in the group, only ranked once, never got a reputation as a major senpai within the group. Still, she is a major workforce in the theater. If she doesnt want to leave, i am not the one allowed to make fun of her. There are other examples for which i actually could not understand why they did not grad already, but i am lacking the suffice knowlegdge. Kojiharu for example - she seems to be on her way to a major model career and has anything achieved with AKB48, but yet seems to be really afraid of leaving. Girls need to be careful of the right graduation timing. Also, Acchan not doing spectacularily well, but just well, may also influence other members in their decision making.