Systema is a compolation of various martial arts. It is based on filtering dwn the most effective styles and moves that the Russians have encountered throughout history, from battles with the Turks and Parissians and the mongol empire and so on. It was "perfected" during WW2 by Stalin's Falcons (personal body gaurds). It's teaching methods focus on quick comprehension and easy learning. Integrates H2H, striking and grappling, with dissarms, confined space, combat and submissions. There are no "proper" stances no katas, no learning to count in Japanese or anything like that. Just fighting and killing.
Practice doesn't make perfect, practice makes permanent. Perfect practice makes perfect.