I don't think air in the system is the issue. Dealers don't mess around with bleeding funnels and wasting time idling the car until the thermostat opens. They use a special tool to vacuum fill the system leaving no air pockets, same as the factory.
https://www.uview.com/index.cfm?dsp=...productid=5120
No issues with heat after I did the flush/fill on my car using this tool. Refilling it took all of a few minutes.
More than likely the thermostat is stuck open.