I have had flutter in the past and caused catastrophic airframe failure. I seal all my hinge gaps with clear monokote now. No more flutter. Something else worth mentioning is that I always overpower my planes and that increases the need to seal the hinge gaps. In the past I used to nearly double the recommended engine size. Speed became a problem and likewise flutter.

I can say that it can only help to do it. With a bit of covering and your sealing iron a 40-60 size plane can be done in about 15 minutes.