> This is significant - if your organization only uses a few dozen base images from DockerHub, those images will only be downloaded by each build node _once_, t

> This is significant - if your organization only uses a few dozen base images from DockerHub, those images will only be downloaded by each build node _once_, then never again. You're assuming that the set of build nodes is relatively static. Plenty of architectures set up autoscaling for the underlying nodes, that terminate servers that aren't being used and relatively soon enough (tens of minutes, hours) spin up new servers to replace them as needed. Rarely do the machine images used to spin up new servers include the base images of the containers that will be spun up to replace them. Much more often, the base machine image is a base OS image, and container images are downloaded on-the-fly as needed. Essentially, the engineering cost of making image-launching more efficient was externalized onto an external provider willing to pay the price.