This is a question that comes up a lot during planning meetings for Agile projects. Each product, story, feature, etc. ought to have a definition of when it’s “done”.
Recently, we’ve seen an excellent example in our industry. The end of XP…
It’s done. No more work will be done on it. No more support efforts will be provided. It’s dead. Finito. Walked the plank. Entered the great unknown from which none ever returns.
This is actually very useful for us in planning. Ask yourself, when the issue of “done” arises: at what point will I stop working on this.