My GC (2013, R/T, red) is my first auto car in 21 years. I have always drive with a stick and for me, it's natural to use everytime parking break.

Somebody told me I should no use parking break everytime, since they are not supposed to be used everyday in a automatic-transmission car.

Should I listen to him or should I ignore him and keep using the parking break ?

 

I have no idea why it would be a bad idea to use the parking brake with an AT; the transmission and parking brake are not connected except more recent vehicles have an electrical connection to warn you if the parking brake is set with the car in gear and/or in motion. You probably don't need to use the parking brake every time you park with an AT but you should definitely use it any time when parking on a hill. Aside from the hopefully obvious safety reasons, setting the parking brake before shifting into park and releasing it before shifting into gear helps reduce/prevent the thud that often comes shifting with out of park on hills (I'm pretty sure that thud condition isn't good for the transmission either).

I have actually heard the opposite: it's actually bad not to use the parking brake on a regular basis, as this can lead to rust and other crap gumming up the parking brake cable, preventing the parking brake from working when you need it.

I have always driven AT vehicles and set the parking brake every time. If we weren't meant to use the parking brake with AT, why would they include it on vehicles like the GC that don't have a MT option? In cars with hybrid drum/disc parking brake setups (e.g., the Caravan through 2007) deleting the parking brake would save quite a bit of weight and complexity. It is a safety feature that is meant to be used, so go ahead and use it.