I am a Reiki Master Teacher and have trained in a tradition that is passed on in person from Master to student. My Master teacher passed on her knowledge to me and can be traced back to Mikao Usui.
In Usui’s time this would have taken years – rather like an apprenticeship. However, in the West, Reiki is often taught over a few days.
I teach Reiki over two consecutive days, usually a weekend, or spread out over a six week period - 2 hours per week. The classes are small and give you time to understand what Reiki is, where it came from and gives you time to practice and be comfortable with the system.