I read the essence of that statement without the same time constraint applied to it. i.e. the type of 1000 lines you should be working on each week is the type

I read the essence of that statement without the same time constraint applied to it. i.e. the type of 1000 lines you should be working on each week is the type (systems code) that enables (application) programmers to write the rest of their code effortlessly. e.g. Rails core (system) vs people who use Rails (applications).