No Docker for us. I baked all dependencies (DB/Redis/etc) into the main image with the GitHub runner to maximize performance. This works well for us as a relatively small product team that tightly controls all environments. Modularity and flexibility come with a cost, and it's not worth it (for us).

One alternative is to use Firecracker on the CI host and run entire VMs for jobs (still quick). However, I am not comfortable with that stack to do "set & forget" implementation with no ongoing burden.