Hello,
Nevil, with docker you work locally and do everything like preview changes, save etc all locally. As soon as you save a change it is visible on the local docker target immediately.
When you are finished adjusting everything, you can then deploy it to the remote target. That's the point of docker - you have the same server, database and settings locally where you work and as soon as you are done you just deploy the same (files, database, server, settings) to your remote server.
That's not true Brian, your logic is wrong, as I explained - when working with docker, on save you get the changes immediately available.
Deploy is only required when you are finished working on the project and you publish it. This has nothing to do with how ftp and ftp targets work.
I.e. you don't need to deploy on every save, as you have the same/everything already locally and you work there. As soon as you are done with your changes and are happy with the results you deploy them to your remote docker machine.