Interesting, so does it keep all the intermediates from previous builds and then does an incremental build on top of this? Like doing a local dev build but in the cloud?
Yeah at a high-level, that's how it works. However, the incremental caching part does require remote caching of artifacts, so that they can be shared across CI jobs/runs.
We've had a lot of success with Brisk (https://brisktest.com/) doing this exact thing. It keeps our environment running so we don't have to rebuild on every run, kind of like a dev build. It's really fast.