While that's true, you or your company have to standardize on a base image to get benefit of shared image layers. In my job, I rarely have an exact match on th

While that's true, you or your company have to standardize on a base image to get benefit of shared image layers. In my job, I rarely have an exact match on the base layer because I'll use images from Docker Hub. Although many of those images use the same small set of distros (Alpine, Debian, or Ubuntu), any given image is likely from a different base version of that distro, thus there is no common base image. There may be differences in the base image even if you use the same tag since the same image may change over time. Thus if you pull debian:bullseye today, and then pull again tomorrow, you may have two different images. Generally I don't bother trying to get a common base image and I'm happy enough just attempt to lower the overall size of my images.