When should you give up on a search term?

How long should you wait before giving up on a specific key word? Is there a general guideline to go by?

I'm targeting some pretty broad keywords and there are other sites that have been around for years.

Never give up! Things take time. Keep creating content around your keywords. Specify out a bit if you need to, but don't lose focus on your core.

Originally Posted by Brian Cummiskey

Never give up! Things take time. Keep creating content around your keywords. Specify out a bit if you need to, but don't lose focus on your core.

Yeah I guess if you go at it for a year and then change it you just lost all that time you spent for the year.

I say never give up as well, if anything, try to expand on the phrase.
Like if you are trying to target blue widgets, maybe try "brand new blue widgets" and see how that works.