The firewalls in what might be all of the ARFs nowadays is liteply. Yeah, LITEPLY, which is actually plywood in name only. It's a somewhat strong, light wood layer with a veneer layer on either side. You can usually break it with your hands. It often has weak grain running through the single thickness of the center wood. And ARFs nowadays use two pieces sandwiched together for firewalls. Hey, it works ok for awhile if nothing much happens to it, right.

Stick something to it with 5minute and the epoxy might not even penetrate the veneer. It'll stick to it no problem, but 30minute often penetrates and sticks the veneer to the center better than it was glued in the "plywood" plant.

Penetration is one of the huge reasons to use epoxy. It does more than stick two pieces together.