All I am saying is make sure the brake pads are set up correctly before adjusting the pre-set spring tension. The vast majority of the time the arms don't hit the rim and return to their resting position is due to the pad setup. If the pad setup is symmetrical then by all means adjust the spring tension.

Say you adjust the spring tension to make the brakes work seemingly correct when the pads aren't aligned properly. And the next time the pads are installed correctly, but now the pads won't be centered and hit the rim at the same time because of the prior spring adjustment. So the mechanic happens to take off the side that wasn't adjusted the last time and now you have one spring with max tension and one with minimum tension. Just do it right the first time. I originally said it's ok to adjust the spring tension, but only after making sure everything else is correct.