We have flown with Copa to Cancun and Punta Cana since 2014 and as recently as Dec 2022. Terminal 2 was recently opened in Panama so the airport has expanded. You're right in that transitting Panama airport there's no need to go through immigration or customs. They start boarding their flights approximately 1 hour before so if the layover is only one hour, it means they will be boarding when your flight gets in. In Dec it took us about 20-25 mins from one end of the airport to another as we flew in to Terminal 1 and our connecting flight was in terminal 2. The terminals are connected so you can walk from one terminal to the other but my recommendation is for a layover minimum of 90 mins. Never know if your flight into Panama may be delayed a few mins so better to be safe than sorry.