And here's a good example Geo with eur/usd, I took a short on Fri based on confluence of these levels.
Looking at the Daily chart, on thurs 13th price reached the 61.8 fib of the swing high 3/5 Aug to the swing low on the 12th, which coincided with strong resistance on the 2/3 june at 1.4309.
Price tested and rejected this level again on the 28 jul, this also being the top of the left shoulder of the potential h&s which was confirmed on the 14 aug.
If you drill down to the hourly chart on the 13/14 aug, price is ranging in its channel, I took the trade when price was at the top of the channel and broke back below 1.4300 level on the 1300hr bar.
I personally dont take a trade based on fib alone, but as you say it works well in FX, when supported by a strong S/R level.