The answer to that question mostly depends on the person in question and what exactly he's stuck on.
All I can share is a little personal experience. I started early 2000 and lost a lot of money in the dotcom bust. For many years I never quite figured out what the mistakes were, until I read the market wizard books and ROSO. For me they were very enlightening, and brought into sharp focus my mistakes over the years. Without the painful experiences to reflect on, the books' messages would not be nearly as powerful. Without the books' focusing effect I might have figured out everything eventually, just a bit slower.