I've had a project manager (very insightful guy) tell me something similar before. He said "as you get more experienced you'll (ideally) write less code and instead reuse code from libraries you've written in the past". I've always wondered how that works for someone? I'm assuming certain projects will have requirements where specific technologies would be used in the front-end and persistent layers depending on the kind of project you are building and so those wouldn't be as reusable but perhaps algorithms you've written before might be reusable on the computational side of things. Like perhaps if you had a library that handles very advanced moving cost calculations you could ideally use that same library in different software forms (mobile, web, desktop, command-line).
Edit: Git might be a good example of a library that can be reused a lot and used within many kinds of applications (IE: inside web app, within IDE, from command-line, desktop app, etc)