Do You Know When to Quit?

I don't know about you, but I often have trouble when facing challenges knowing when to press on and when to change direction (i.e. quit).  I feel like when we're growing up we're always told "If at first you don't succeed, try, try again". When does this cycle stop though? Are we supposed to spend our lives repeatedly attempting to fix an issue, a person, a relationship, etc. when really we just need to cut our losses and move on? I ran across this article about knowing when it's time to quit, and I think its sentiments are something to, if not take to heart, definitely dwell on as we go through our lives.