Replying in series as I see more of your edits: > For instance, mounting a volume that can be edited by other containers lets me insta-move large files or sets

Replying in series as I see more of your edits: > For instance, mounting a volume that can be edited by other containers lets me insta-move large files or sets of files between steps of containers, As long as the containers are on the same docker host, many containers can mount the same volume.