Another thought on when they are needed. Look at the math for a basically modified street car on stickys that hooks, even running 14.0s.

3.91 gears, 3,000 stall converter, mild 440 ,450 ft lbs torque at stall speed, no spin.
Torque x converter torque multiplication, times trans ratio times rear gear for the torque at the hit.
450 x 2 = 900 x 2.45 first ratio =2205 ft lbs x 3.91 rear gear = 8621 ft lbs of torque working to hurt your chassis! Now take the spring front segment length to figure force on the spring hangers.
8621 divided by 20 inch times 12 inch = 5173 ft lbs load, divided by two hangers, or 2586 lbs of force on each hanger.
It may only last the first two feet, but that is where max torque to the tires will be.