Test #1:
Stuck a socket inbetween the brake pads. Duct taped the caliper away from the rotor. Brake fluid system intact. Drove for ~5 miles.

Results:
Left rear brake area was as cool as a summer lemonade! Pretty cool...being slightly elated I decided to check ALL the other brake areas.
Right rear was warm but I could keep my finger on the rotor hub.
Left/right front rotors were so hot I could not keep my finger on the rotor surface. I could only touch & instantly pull away!

After test #1 I reinstalled left rear caliper & test drove. Warm to the touch like the right rear. No intense heat. Front rotors still high heat.

WTF!!! I didn't check all brake areas before test #1 but I have now ruled out the parking brake for causing the heat buildup. But now it seems I'm getting some extreme heat at all brake areas, especially the front. The only thing that is common to all 4 brake areas is the master cylinder. Could the master cylinder cause all brake pads to stick to the point of high heat buildup? Braking is normal. No noises.