First you ask how to use it, then you say right ahead that it's not worth it?
As other members have said, you're not obliged to use it.
As for myself, I find it very reliable for take profits, for instance.
Around 50% or 61.8% retracement. Many times the price rests there before continuing the trend or turning around.
For example, this very recent EURUSD 4h the 50% retracement is right on the pinbar:
http://i.imgur.com/MyMVe.png