Yeah - you will be pi$$ed if the stocks close today at $25. (not)
My not so absolute rule is I buy or sell 10% of my holdings in F&F for every 20-25% move. Subject to excitement/greed/pessimism/stagnation causing me to adjust this a bit. I always have some limit/gtc buy and sell orders in at the edge of those ranges.
Lately just a few trades since even though it's been up/down more than usual it has not hit many of my triggers.