In my (all-too-lengthy) charting experience, I have found some charts are especially "Fibonacci-friendly" when it comes to fan lines and retracements. One such example is $SPX, the S&P 500, and its fan lines.
After Friday's sickening surge, I was curious to see what was going on with the S&P from a long-term perspective. I took great interest in how the very long-term fan line (dating back – I am not making this up – eighty years) was asserting itself as resistance. Look at the areas I've circled to see how this line has behaved as a magnet for prices.
Looking at the past fifteen years or so, you can see how fan lines from another series, also dating back to 1932 (but whose end point is in 2000 as opposed to 2007, as the prior one) have proved themselves amazing levels of support and resistance.
