If you use the proper size and number of rubber bands, the wings will not move in flight, and they can help let the wing pop loose in a crash instead of breaking. But many people think they need to add extra rubber bands for safety, this can make the rubber band mounting stronger than wing bolts, resulting in more damage when a crash occurs. You can check your rubber bands to see if they are adequate. Make sure all components are installed and the tank is full of fuel, hold the plane by the wings close to the root, carefull not to grab an area with weak sheating or no sheeting at all. Raise the plane up and down as quickly as you can and observe how much the fusalage separates from the wing when you start to raise up. If you are moving it vigorously and you can not get the wing and fuse to seperate at all, you may have too many rubber bands, if you get a minor seperation, like an 1/8" to 1/4", you are probably about right.