I do same for my portfolio. For each equity position I have both buy and sell limit orders placed at predetermined prices...good till canceled. When an order gets hit I in-turn recalculate using the Quick Aim Calculator, place the new buy and sell orders and go play!
I used to do the exact same thing, but now only place GTCs on the Sell side. I do set alerts for both Buy and Sell prices so am informed when my next price has been breached. I get these on my phone, tablet and regular email. Now I admit, I've missed a few opportunities from time to time where the price drop was very short term, and I wasn't in a position to follow through at that moment in time, but I've also chased enough falling knives over the past 15 years that I want to check a few things before I pull that Buy trigger.