Several months ago, I started making a paper-pieced hexagonal quilt. For fabric, I culled out some old baby clothes, so I could use the better parts for the quilt. I was planning to make a small lap quilt or a pillow cover.
I like the technique, because the paper templates make the piecing and the hand stitching come out very precisely, making my sewing look much better than it actually is. But I didn't like how this particular project was turning out. I wasn't enjoying the fabrics, or the thread (the only color that I have in any quantity in the moment is navy blue), or how they went together.
So I let it go. I officially declared it a UFO--unfinished object--and it went into the donate box.
I was going to get rid of all the unused fabric too, but then it occurred to me that I could use it for one of the kid quilts that I am planning. These will be more in the style of utility quilts, made of simple and somewhat large squares. So I made a template for a square from sandpaper (that's what Grandma used to do, it goes grit side down on the fabric) and started cutting out squares. Now I have about 100 squares, which is a good start.
How do you know when to let a stalled project go? I learned from Barbara Sher's book Refuse to Choose that it is okay to let a project go when you have gotten what you want from it. This is not always a completed project. In this case, I got the satisfaction of mastering a new technique.
In economics, there is the Sunk Cost Fallacy, which says that you should let an investment of resources go when it no longer makes sense to keep it, no matter how much you have already sunk into it. Admit the failure, and move on. With the quilt, I realized that I was not going to get the satisfaction of a finished project that I loved, no matter how long I worked on it. I cut my losses and went on to the next project.