That's pretty much exactly my recommended approach for both training people who are new to software development and bringing an experienced developer onto an ex

That's pretty much exactly my recommended approach for both training people who are new to software development and bringing an experienced developer onto an existing codebase (or language, or platform, etc) they haven't worked with before. The only difference, per individual, is how long they need to spend at each level before moving on to the next. When you get into real-world software development, it's much easier to work with an existing codebase than to start from scratch on a new one. If the application is in production, then you know that the existing code works, so you've got a baseline. You can study it to figure out how it works, and you can compare that to requested changes in the way it should work, and then you just need to figure out how to change the code to make the behavior change. That leads you to asking the right questions, focusing on the right code. It's like the hand-holding phase, except it's real code instead of play code. Figuring out how the code works also teaches you a bunch of stuff on the side, like how to do debugging in this new codebase, how to set up and work within your development environment, the practices and patterns of your team, etc.