I am not a pro but have learned that in most combination gas furnace/ air conditioners the air flow is sized to keep the heated air way down at a very safe level so that a child would not get the mildest burn from touching a register. This faster air flow is then not “ideal” during air conditioning season to remove as much humidity from the house air.
My HVAC was replaced some years ago. The new unit uses a motor controller to control fan speed, much quieter than the the old one that is for sure. The fan usually runs 24x7 at low speed to keep the house temps stable, winds up to high speed as the AC or heat comes on. Even teh compressor fan is controlled, much quieter too.
I wonder if it is setup to consider your above observations, since that is entirely possible in software? I never noticed. Did have hte air flow balanced. Used to be the front bedroom got all teh AC or heat. Turns out the old plenum was shaped to direct all that flow to that room. Had a new plenum built and my AC bills have been about 1/4 what they were with all the changes made.
