Warning: SPOILERS for Cobra Kai Season 4.
Samantha LaRusso (Mary Mouser) didn't strictly rely on Miyagi-D0 karate in Cobra Kai season 4's All Valley championship final against Tory Nichols (Peyton List). Cobra Kai season 4's All Valley tournament changed its format to create a boy's and girl's division as well as preliminary rounds that feature skills. Sam surprised Tory by changing her fighting style but it wasn't enough to win the championship, although LaRusso and Nichols were unwitting victims of cheating by Cobra Kai's sensei, Terry Silver (Thomas Ian Griffith).
Sam may have been the late Mr. Miyagi's (Noriyuki "Pat" Morita) last karate student. The favorite child of Daniel LaRusso (Ralph Macchio) learned her first karate moves from Mr. Miyagi when she was 8 but she stopped training until she became a teenager. In Cobra Kai season 2, Sam joined Daniel's rebooted Miyagi-Do dojo. Daniel's daughter is a natural karate kid and Sam became one of Miyagi-Do's best students, along with Robby Keene (Tanner Buchanan), who eventually quit Miyagi-Do and defected to Cobra Kai. In Cobra Kai season 4, Robby taught his Cobra Kai cohorts Miyagi-Do's defensive style, negating the advantage Sam and her friends had by learning both Miyagi-Do and the offense-based Eagle Fang karate system of Johnny Lawrence (William Zabka) after Daniel and Johnny agreed to combine their dojos.
In her All Valley final against Tory, Sam combined both Miyagi-Do and Eagle Fang's styles into "Miyagi-Fang," a hybrid mode of fighting that was uniquely her own. Sam was well-aware that Tory knew Miyagi-Do's counter moves so, with both Daniel and Johnny's blessings, LaRusso finally fought the way she wanted to fight. When Sam combined Mr. Miyagi's katas with Johnny's "badass" offense, she scored her first point against Tory by unleashing the flying tornado kick that Sensei Lawrence taught her, unbeknownst to Daniel. But Sam's arch-enemy Tory is also a formidable fighter and she used her own hybrid of Miyagi-Do's blocks and Cobra Kai strikes. What neither Sam nor Tory knew was that Terry Silver paid off the referee to score in Cobra Kai's favor. Tory won the fight but Samantha technically beat her by scoring a point that the corrupt official ruled was out of bounds.
Sam merging Miyagi-Do and Eagle Fang, which is really just Johnny's version of Cobra Kai, into her own system brought LaRusso's Cobra Kai season 4 arc to fruition. After numerous altercations with Tory and Cobra Kai outside of the tournament, Samantha was frustrated and felt limited by Miyagi-Do's tenets of karate only being used for self-defense. A hothead like her father, Sam was intrigued by Johnny preaching "striking first like an eagle" and LaRusso correctly realized the best way forward as a karate student was to learn both Daniel and Johnny's styles.
Sam's journey is the true theme of Cobra Kai season 4, where even Daniel and Johnny eventually realized that their stubborn belief that their way was "the only way" wasn't true. It was Samatha who fully understood that she didn't have to hold on to her dad or Johnny's bullheaded viewpoints and that she needed to forge her own path. Taking both styles of karate and incorporating them into "her way" is what every student in Cobra Kai needs to do going forward, not just Sam.
The heartbreak for the young LaRusso is that, despite doing "everything the right way" with her incredibly effective Miyagi-Fang hybrid, Sam still didn't win the All Valley, although she doesn't know Terry Silver cheated. For Sam and Daniel LaRusso, not winning the All Valley was a terrible humiliation that cost them the Miyagi-Do dojo. Still, Sam unifying Miyagi-Do and Eagle Fang's karate into her own personal style is the future of how Cobra Kai's students will learn their favorite martial art. All of the karate kids using hybrid karate the way Samantha and Tory did will make only Cobra Kai season 5's fights even more thrilling.
Cobra Kai season 4 is streaming on Netflix.