The key is to learn only what you actually want to use. Then because you use it frequently you won't forget . Then when you want to use more of the instruments capability , think of the practical scenario you want to use it and then learn that function and use it accordingly . I have had my instrument 10 years and to some ,I know it inside out , but I know there is a good 30 percent of it I have never used and most likely will never use . E.g. I have never used the vocal harmoniser !!! I have done minor sound editing and use this only when I want to mimic a sound from a song that was not close enough on my standard keyboard . In other words very rarely . You don't have to be an expert at everything . Just be an expert at what you do .