Depending on where you go to study, there are auto schools to learn theoretical expertise, auto repair shops to learn operation, and school study: internship after graduation. Time is when you graduate. Studying in the garage, some for one year, some for three years, depends on your own efforts. But repair is a technical job, and we should learn from the old ones. Just like the car I'm driving now, a problem has not been solved by many repairmen, including myself. Look at your understanding.