How and when do you guys determine a project is finished?
When it can be driven? When it is painted, or just before it is picked up by the new owner?
Do you ever stop working on a project?
Its finished when the original plan is accomplished. When the things you deem "necessary" are complete. Anything after that is just modification of a completed project.
With my kart. I have tons of things I want to do but it was "done" as soon as it drove safely. That was the goal. The other stuff may get done, may not.
You can even change your plan before the original plan is finished, keeping it incomplete where previously it would have been complete, had you not changed the plan.
You can even modify it in a way which renders it inoperable, its still complete and only in the process of another modification.