I still have the box and two blocks and fabric from my Bi-Centennial quilt, started in 1974. Does this make it a work in progress, a work forgotten in the process, an abandoned quilt. Or, one that had good intentions to begin with but dropped by the wayside. Perhaps it is time to let it go and use the fabric for something else. But this doesn't answer your question which is about a quilt that is worked on periodically and not abandoned to the back of the closet.
I have one that have been working on now for about a year and do pick it up occasionally to make a few new blocks.