Here's just a little analysis
Something that has always bothered me is that people tend to use how Sakura acted in The Land of Waves as a justification for calling her "useless" or "weak." Unlike the MAJORITY of her classmates, she did not come from a clan, nor was she raised by shinobi. The life of a shinobi was something completely new to her. Her life was not marred by tragedies like Sasuke and Naruto; she did not have to fight for recognition, acknowledgment, or to prove herself. Unlike Ino, Shikamaru, and Hinata, to name a few, she did not get the teachings of the clan nor the expectations that came with being part of a clan. Her reactions to seeing her friend basically die and violence is entirely NORMAL for a twelve-year-old girl who has never seen such things before.
Her fears and insecurities are valid, especially since she watches everyone else move miles ahead of her (and we can certainly discuss how Kishi wrote her, but that is another post entirely). She was at a point in her life where she was wholly impressionable and put her faith in people who were superior (i.e., rank. In other words, people with more authority than she). But what else do you expect of someone thrust into a world she knew nothing about? Sakura came from a rather nuclear family, and while we are told her mother and father are shinobi, we do not really see anything until the war. So when we get down to it, she was raised with no shinobi influences whatsoever. She does not seek nor need recognition or a family in the sense that she already has that (she gets recognition from her parents). So while her parents might not be shinobi, meaning their household is not suitable to raise her as a shinobi (they don’t know they life). If it were, she would have better understood what it means to be a shinobi and the road that lay ahead for her. (Of course her parents being shinobi or being civilians is never explicitly stated so here there is room for speculation).
Due to childhood bullying, she has a warped sense of self-worth and how she sees herself. This can be seen in the way she questions herself and, at times, seems uncertain of what she is really doing. But again, that is at no fault of her own (especially with the stigma of female characters in shounen characters. She is a character at the mercy of her creator and used as a trope to highlight Naruto and Sasuke's strength. She is never really given a chance to prove herself because she is written off as the character that needs to be saved. This notion in of itself is highly contradicted by her physical strength and how much character development she had, but I digress).
Sakura worked extremely hard for what she has now and has become, and she did this for herself. The exams were the final push that she needed to have enough introspection to realize she was relying too much on her teammates. Sakura had enough analytic abilities and understanding to blindside Sasuke to k.ill him when he was at his most vulnerable moment and found a literal goddess's one weak spot. Additionally, the violence she demonstrates and uses on and towards Naruto is amplified in the anime more than in the manga and taken too far in order to be "comedic" when it is NOT. In the manga, it happens less frequently and is not used as a trope for "haha look at this it is sooooo funny." The anime used her for trope purposes more than showing us the growth that we see in the manga.
In many aspects, she was "just there and needed to be saved" in order to highlight our "true" main characters' powers and abilities — Naruto and Sasuke. She had one of the best character developments but often got reduced simply because people do not want to admit she is a strong female character with faults.
