Back in the days of Nitro the motors turned a lot higher rpms. We used to fly at the salt flats. Yes the same ones that a lot od land speed records were set. Around our field we dug two ditches that would fill with salt water as the rain fell. The ditches kept the cars from leaving trenches in the salt flats. If you had a bad landing it was not all that uncommon to end up in one of these drainage ditches. Most of the time you could just go and pick up your plane clean it off and keep flying. Once, while flying a quickie 500 pylon racer I did just that. Ran off the end of the runway and into the ditch. The plane hit the salty water and splashed up on the airplane. So we cleaned it off and kept flying. I was looking up at my plane and could see something hanging down from it. So I did a low and slow flyby. It was the aileron! It was hanging straight down! What could have happend? I quickly landed the plane breaking the aileron off and when I looked at it all three hinges had not only broken, they had melted! This was caused by the salt water that had gotton on the propeller and left salt crystals on only one of the blades. I remember that plane well as it was clocked at 180 mph. The engine would turn a 10/6 propeller 13.000 rpm on the ground and it would unload in the air to maybe 15,000 or 16,000 rpms. At those speeds just a little out of balance can tear your plane apart. Now a days with electrics we turn much lower rpm's. I fly mostly at the park now and don't worrying about the prop balance as much.
Then I got my speed wing.
it uses a 3000 kilovolt motor on a 3 cell. It turns that prop fast. Guess what? I am back to balancing my propellers. Should you balance your propellers? The answer is yes always. As your skills get better your planes will get bigger and faster. It is better to practice good habits now, and as always. Safety first.