If by short trip, you mean to the end of your driveway, or you have a crystal ball and are 1000% sure that you will not have an accident or that somebody won't cut you off, then by all means, leave it out or off. Unfortunately, we don't get the luxury of knowing when something is going to happen. If you get into an accident, and your state requires an auxilary brake on your toad, and it isn't there, you may as well paint a bullseye on your back.
The lawyers will be standing in line to take that case.
This topic has been discussed over and over and over again. If your state requires it, put it in. IMHO, if your state doesn't require it, put it in anyway.
If I got into an accident and somebody got hurt because I couldn't stop in time, regardless of the state law, that's not a burden I want to carry.