This reminded me a lot of The Manager's Path, by Camille Fournier. When I was struggling to figure out what direction I wanted to go with my career, that book helped me out a lot!
Having a clear idea of the levels of development is super helpful, both at a personal level and at a company level I think.
Nice! I had never seen that book before but it's pretty much what I've been trying to do with my newsletter "Navigating Your Software Development Career". The term "navigating" happens to be in the book you mentioned, which, as you said, is helpful to know where you are "going", etc.
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