Why am I so compelled to create things? At times I am totally posessed to spend large sums of time on projects that may or may not be successful, and yet for the most part, it really doesn't concern me. I have, without a second thought totally scrapped something I have been working on, losing 20, 30, or even 40 hours of invested time. Of course I do want a project to offer a return for the time spent, but I realize that I'll win some, lose some, and the success comes not from a single project, but from the full portfolio of work.
That being said, there is a need to evaluate the potential success of a given project to ensure that it is worthy of my time. After all, spending time on an unsuccessful project just takes away time I could spend on something more lucrative.