I'm only doing a great job at it because I'm calling out Sakura's flaws. It's not my fault if she has more then one.
And you're right, Shizune said she was storing it for years. She said that while Sakura is about to unleash the chakra so that doesn't counter anything I just said about the powerup coming out of nowhere, because the explanation is just on the spot as the jutsu is about to be used. Still cheap. As for Sakura in the Pain arc, Pain was attacking long before Naruto got there. As for Iruka telling Sakura to go to the hospital, if Sakura has Tsunade level strength with the forehead she could have told Iruka that she could help Tsunade protect the village the same way Tsunade did. If she is like Tsunade she can't die easily and Konoha does have other medics. So why has it taken Sakura this long to reveal this justu when there have been plenty of times she could have helped? Sakura's sudden boost of power makes zero sense and is cheaper then anything Sasuke has done. To compare the two is laughable. Yes Sasuke gets plot armor Uchiha powers, but he gets fight after fight after fight to buildup to his evolving Sharingan. Sakura has none of this and then we have to accept her as a Sannin?
To Besho. I agree with that completely. The Sasori fight IMO is Sakura's greatest moment in the series. I wish she had more of them.
RIP anime version of Glovehead. Pokemon Adventures will save you.