Goodman HP central AC

No. It is only used when the pump cannot keep up with the heat demand of the house or during pump defrost.

Why do you think it is coming on?

Some very high end large commercial/institutional specialty units for hospitals/research labs/computer rooms have complex 2 deck heat/cool units. In one area you may need heat and another cooling. They may use elec reheat strips or coils/systems. I worked in a Convention centre and we had such equipment.

Not in resi though as it would cost to much and the homeowner would scream when he got his elec bill.

When the unit shuts off outside the fan may have a setting to run for a few minutes to extract the cold out of the coil. Should not smell. May want to get a tech to check the coil for mold. Apparently in humid areas of the US that happens and they need UV lights to prevent it.

If you have a elaborate thermostat that has a dehumidification feature it may turn on the heat strips and AC to just dehumidify and not cool the house down.

Not something I run into as my area is medium humid and AC not a big deal. Usually around 50% RH in Summer.

However the communicating tstats have all kinds of fancy schmancy features and programs.