Question: When is it okay to put away something you started and finishing it?
 
Answer: Any time you are dragging yourself to work on it.
 
That seems strange to those of us with strong work ethics and the inviolable policy of finishing what we start.  But writing that no longer excites us is most likely not going to excite readers either.
 
Pay attention to that sense of needing to put something aside. Maybe it's not working because this is a project that is past its prime.  Perhaps it has a fatal flaw that requires distance to detect.  It could be a project that just no longer is interesting or relevant to you.
 
Our motto with writing projects that we aren't under contract to finish is that if it's not getting us out of bed in the morning with at least a pleasant anticipation or an engaging challenge, then it's time to work on something that really does call to us.
 
What projects have stalled for you?