During this recent cold spell, the electric central heat could not maintain a temperature at two of my properties.

#1 Townhouse in the Houston Galleria area set to 70 and would drop to about 62 at night. Heater ran nonstop for 2 days and never made it to 70. Finally made it yesterday to 70.

#2 Piered/crawl space house in New Orleans. Also set to 70, and would drop to 55 at night. Heater has not stopped running since Friday and still has not made it back to 70.

Is this typical? I've had gas heated houses before and there was never an issue. I imagine insulation may play a role. But, 55 is ridiculously too cold. Could it be a thermostat limiting the heater? Any thoughts, comments, and suggestions are appreciated.

What was the temperature of the air coming out of the vents?

I wasn't at the NOLA house (Wi-Fi thermostat) and didn't think to check in Houston. What should be the differential between vent and register for heating? Same for AC (15-20 degrees)?

Limited data forces guesses ala

1) undersized units to achieve 70/25 in/out temperatures
2) leaky ducts (all ducts leak a little but this report may say a lot)

Lots of questions an expert HVAC guy would pose before suggesting ideal answers w/o an on site inspection

Same problem in Feb 2021?

No that's not normal. Unit could be under sized or most likely, the heating element could be bad.

NOLA HVAC company coming out in the morning. Will report.