[judge2020]

The definition is sourced from here[0], and says "Each check-in is then verified by an automated build, allowing teams to detect problems early.". It's not a hard rule to "not run on every dev branch".

"continuous integration" is often just "npm ci && npm run build", and sometimes "npm run test" (or similar for your language). For products that don't make any remote API calls (or when they use a faker service), most of this is done on the same machine and costs very little to do on every commit, making it easier to precisely define which commit broke something.

0: https://www.thoughtworks.com/continuous-integration