I think it works best for advanced players in general. I was referring specifically to beginners when I said it only works well with a great Rabbath Teacher as a primary method from the ground up. I spent time with a teacher two degrees from Rabbath in my 20s and It was great - after Simandl. Any advanced player can get a lot from the books and we should all have them. It is a more complex method and in some ways more self contained than Simandl. To get to the same place in 2017 I use Simandl, Petracchi and Bach, as well as other solos - I actually like having the "other opinions" and having a more open and modular system. Still, there are many great bassists who came up on Rabbath as well as top professional bassists who have added it. To move this back on topic, consulting multiple systems and have several fingering solutions to things is much better than thinking about positions.