ALL THE TIME! Truly, every project I work on I get to this point. I think I have ADHD or something when it comes to my quilting because once I begin a project my mind wants another project.
I think if I had to pin point why it would be because I love the process of picking out a pattern, choosing the fabrics, cutting the fabrics up, and sewing the blocks, but once the blocks are sewn I'm bored already. I would hire someone to piece them together into the actual quilt top if I could.
I'm sure this is why I have at least 15 or 20 projects going at all times. Not good, since it means I don't get much completed, but it's just the way my mind works.
So, don't feel bad...you are not in this alone...
Suzanne