Are girdles generally added for big rpm or HP or torque

Hear i go again. GET A CENTER WIEGHTED crank! Ford puts them in stock 5.0 mustangs for a reason. They rev to the moon, and Ford knows the hotrod crowd will push the limits, yet you don't hear of many failures.
Center weighted cranks spread the load to not stress numbers 2 and 4. Number three now has to carry its share of the load. The crank is happy because it is twisting and flexing less.
Guess how many crank failures Ford has had in th stock 5.0? None. Racing? None. And they sell that same stock crank to racers for big power motors.