Rubicon

Please do not use the emergency brake! On most of my vehicles they are disbled already anyway.

Reason for not using the emergency brake is that you will most likely forget to release the e-brake in such an exciting off-road environment as the Rubicon. Since the vehicles are so extremely powerful you will start driving with the e-brake on and won't even notice that its on - the truck will pull away showing no signs of load. By the time you notice that the brake is on (it'll smell bad) it might be so far damaged that it has no more life left. A non-functioning rear brake, however, can be a disaster off-road.

So, to keep the brakes healthy - don't use the e-brake!

Different story on the Jeep TJ with automatic. The emergency brake is a vital part of the gear selector and needs to be activated as shown here.