I've found one 9-words-long keyword phrase in SEO Book, and it had a nice search volume. I copy-pasted it into my article and made a H2 subtitle from it and "covered the topic" with appropriate description (100 words paragraph). The next day, I ranked #2 for that kw phrase. Then...after few days...I'm not even among 100 and it is really not a competitive phrase. ...errmmm Checked now, and...I'm #1 .
That seems to be the pattern these days. I freaked out a little when I saw this happening to a few of my blog posts. I would write the post and rank really high for terms in the title for a day or so. And then gone. A few days later, it was back. I am not sure if Google has some sort of freshness algorithm that gives new pages a benefit of the doubt for a few hours or what. But it sure is interesting.
Happens to me all the time, the first time I panicked, NOW I know it's just the google mood swings. Google sometimes ranks new posts very quickly and then takes them away. And brings back the quality stuff. I think the good stuff always returns, that is quality content, and the bad stuff does not!
You can find out which long keywords are effective for your site from your cpanel data. Long tail keywords are effective in increasing the traffic if you find out and optimize them suitably in your site.
some time long keywords are also effective to gain traffic for your site , but it depend upon how you optimize it and what type of content you have in your site
Could also be described as every action has an equal and opposite reaction. Website owners take a quick action for quick results and swinging one way, then Google recognizes it for a while and passes the site swinging by it like a pendulum.