I have 4 older tops finished up that need quilting and have been around a long time. Two that are heirlooms that are waiting to be quilted that I finished the summer. I have finished and gifted so many I can't count them all though. (Does that count in my favor ...LOL!) Currently I have five in the works at different stages. And three I have bought everything for and waiting for me to make.
My next door neighbor just gave me a partially sewn one from a class she took three years ago she didn't finish. She decided she hated it. I admire her for admitting it and just letting it go. I think we all could take a lesson from her generousity and courage. I am hoping that I can make it alright. She had cut it out completely and stored it in a plastic zip bag kinda wonky and it is a lot of bias edges. We will see ... I think it will be fun to try.
I think that it depends on the person. If it bothers you to have someting waiting for a while. Finish it. I personally enjoy having them around like old friends. :-)
In my defense, I spent the beginning of the year finishing up tons of wip/ufo's. It felt great.