When Good Projects Go Bad

This is a story of a good project gone terribly wrong. It all started one Saturday morning.... 

I was invited to a handmade ornament swap last month for our modern quilt guild. What could be cuter than a tiny quilt block ornament?

I decided to make a Cathedral window mini block. I've always admired hand sewn cathedral window blocks--and this was a good way to try it out without committing to a whole quilt.

 I used the faux cathedral block tutorial from Quilt Bug, and hand sewed the white edges. I highly recommend the tutorial- I had perfect quarter inch seam allowances using her method! It was great! Until...

I fudged the binding, and while I was ripping it out, I cut a hole in the corner of the block. I won't lie-- there were a few tears.

 I ended up turning it in to a circle, and it worked out ok, but it did make me think.

I spent an entire Saturday afternoon on this little project, and was still not happy about the result. I sometimes think that I push forward when I should have just started over with something different. I've noticed this trend with quite a few projects of mine lately. 

When I'm in the middle of working on something keep going thinking I don't want to waste the work I've already done (in this case it was the hand stitching on the block that kept me from moving on), but I end up with things that don't get used because I just don't like them. Any advice?  How do you decide when to call it quits vs when to keep going?