I haven't read it, but from skimming it looks like the tactic is to follow consistent rules for the entire course. The system being built is entirely self-contained, just complete. This makes it a lot easier to build on what you've already done.
In a typical csci curriculum each class will start with its own set of assumptions about which systems are being dealt with and what tools you need to learn. You might take a compilers class that uses yacc, a languages class that uses Common Lisp, an OS class that uses Java and an architecture class that uses x86 assembly. For each class you'll need to spend some time reviewing the tools and systems specific to that class, in addition to spending time on theory that isn't relevant to the focused goal of building a working computer system from scratch.
In a typical csci curriculum each class will start with its own set of assumptions about which systems are being dealt with and what tools you need to learn. You might take a compilers class that uses yacc, a languages class that uses Common Lisp, an OS class that uses Java and an architecture class that uses x86 assembly. For each class you'll need to spend some time reviewing the tools and systems specific to that class, in addition to spending time on theory that isn't relevant to the focused goal of building a working computer system from scratch.