My solution is to have side-projects that are open source, which I reuse across multiple jobs. Wherever possible, I get permission to "contribute patches to Op

My solution is to have side-projects that are open source, which I reuse across multiple jobs. Wherever possible, I get permission to "contribute patches to Open Source projects" included in my contracts, and thus grow the body of reusable code over time. It usually takes some nights and weekends to get the initial body of open source code written, but since it is usually more-or-less a clone of something I've previous written and want to use again, it is fairly mindless effort. If you're in a position where you retain the IP for what you write, (I assume you're permitted to use open source?) you could just do whatever tidyup is needed, and push it to GitHub, ready for reuse?