ORIGINAL: MinnFlyer
And don't do it to prevent flutter - it won't
That's like saying that motorcycle riders shouldn't wear a helmet because they won't prevent deaths.
No, it won't prevent flutter. But it will help. There are many things that contribute to flutter. And reducing each one of them as much as possible will help to prevent flutter.
But the good news is that something as simple as sealing control surface gaps does many wonderful things for your aircraft. It reduces the throws required. It reduces drag. It makes the airfoils more effective and more consistent, especially when surfaces are at high deflection. And as an added bonus, it helps to reduce the risk of flutter.
When I've got over a grand and countless hours invested in an airplane, I find that the mere minutes required to seal the gaps to be well worth the effort.
Dave