My experience is that most Scrum teams define "Done" as a "potentially shippable" story/feature. However, Lean has taught us that this definition actually introduces waste in the software development process.
I like to think of such a "Done" column as "Waste In Progress" and should thereby also have a limit. So, once the waste limit has been reached, it is time to merge shippable stories to the current release branch and deploy a new version to production.
Hopefully I will be able to test this idea in my current team. 🙂