Blower fan speed selection
Most blower motors are 3 or 5 speed motors, though it varies by manufacturer.  Typically they come with heat set to use LOW, cool and fan set to use HIGH.  If it's a 3 speed motor,  the HVAC tech is limited to only adjust to MED.  Whereas if it's a 5 speed, the HVAC tech has more flexibility.  

In most cases the factory settings are adequate.