I check the firewall and usually dowel it as a matter of course. I try to avoid the temptation to slather in the epoxy and tri-stock because I generally build heavy and, for better or worse, the ARFs do seem to come in light. Lighter flies better. I just assembled a Hanger 9 Saratoga 40 and only beefed up the tank area with a cross-wise retainer (the tank was loose in their built in cable-tie strap cradle and pressed the throttle linkage). I gotta say this one is built darned good. I also added a popsicle-stick stop to keep the battery from sliding backwards unnoticed as it was in a foam sandwich held by Velcro. Did not touch the firewall or other spots but I will keep a watchful eye on everything.

On the other hand, I have been leery of the last three firewalls on Great Planes models and pegged them with toothpicks or bamboo skewer dowels. I had one pull loose in flight a few years back and that was no fun - though I did land her otherwise OK. They were probably sufficient, but it's cheap insurance.