HI LEE1 Prop balance is needed most on high rpm set ups, and large diameter props. I buy combat props by the bag full, and I don't spend more than a minute on each one. I use 120 grit paper, and a couple swipes on the heavy blade's tip makes them run smooth, and the fuel doesn't foam from vibration. I would rather shorten one of the tips by 1/16", than mess with the airfoil of one of the blades, plus you don't break into as much of the varnish on a wood prop this way. I run 21K rpm Combat engines all day with props balanced the "WRONG WAY"[taking material off one of the tips], and the bottom line is that it works, and takes less time.