It is my belief that all martial methods were originally intended to give useful skills in a reasonably short period of time. This, of course, depends on how dedicated one is to the training. But in the main, no system should require many years of training before one can expect to have reasonable skills.
Of course one can always spend a lifetime training and getting better, and true mastery may require much more time. But again, that should not mean that one cannot expect to develop useful skills far sooner than that, I would say beginning around 6 months to two years, depending on how dedicated one is to the training.
It is my opinion that it is a new and modern mythology that has been built around martial arts, that one needs many years of dedicated training before developing useful skills. Teachers who promote that mythology are doing a disservice to their students, and may be incompetent themselves.