A friendly counterpoint: my test of new models and agentic frameworks is to copy one of my half a zillion old open source git repos for some usually very old project or experiment - I then see how effective the new infra is for refactoring and cleaning up my ancient code. After testing I usually update the old projects and I get the same warm fuzzy feeling as I do from spring cleaning my home.

I also like to generate greenfield codebases from scratch.