I like how Izzy reiterated on several occassions how he just kept sticking with the same transactional model for success throughout his entire career. Sure, the actual markets being traded may have changed over the years, but the core transactional model never did. I just finished a book called The One Thing by real estate mogul Gary Keller and it reiterates the same point that Izzy did: Choose what your "One Thing" is going to be in life and then become obsessed over making that work and scaling it up. Intense focus and persistence on one thing creates dramatic results over time.
Baron, I was on the Amex when I watched his business grow. I started at a competing floor broker. They were much bigger than us. Then he bought a specialist post, then grew off floor. Really smart and focused. $3B+ later, still doing it right.