Every thing will flutter given the proper stimulus. We get by by having the natural resonance outside the range of the normal stimulus, i.e. keep the natural frequency very high. We can do this by making very stiff structures, keeping any slop out of the control system (no enlarged holes in control horns or servo arms, supporting any long runs of a push rod to prevent flexing, large cross sectional area of push rods, firm servo mounts etc.). While static and airodynamic balance have their advantages they do little or nothing to prevent flutter and improperly implemented can cause flutter. The ideal surface would weigh nothing and be unbendable and would never flutter. Since these are impossible to obtain, we just try to make our structures natural resonance fall out of the range of the normal stimulus of engine vibration and airodynamic turbulance.