^^^ That right there. Though to be fair Tsunade probably made Sakura self-study a lot and work with Shizune as well.
Sakura gets the least focus of the three but she is by far the most interesting and adept imo. She's the best student and she'd have been a fan-kittening-tastic teacher herself---something we never get to see.
Same with Orochimaru and Kabuto, Sasuke even created his own moves without them knowing. The good teacher teaches you how to think and use what you have learned. Both Sasuke and Sakura used their potential. What advice Jiraiya gave Naruto? "Who needs them seals, let's become 2 trick pony!" and he basicly facerolled enemies, and only got to learn his element far later, falling 2 years behind Sasuke on that part.