It takes just a minute or two to walk around your truck. It can save so much more. It is a good idea to do a quick walk around your truck after every break, even the shortest ones. EVEN IF YOU ARE IN A HURRY, MAYBE EXPECIALLY WHEN YOU ARE IN A HURRY. One of the most common post accident phrases is "I was in a hurry.". Do a quick walk around. Reach in and hit your lights and flashers. If you have a light check switch, use that. You may not even have to climb all the way into the cab.
Are your air lines connected properly. Make sure that they are snug. A loose line now, may become a disconnected line down the road. Why take that chanc? Check your 5th wheel. A tug test is always a good idea, but get a visual as well. Someimes a tug test will stick. Getting a visual a long with the tug test is worth a few seconds. Some clown may have pulled it. It is a lot easier to reconnect before you drop it and end up with your picture on face book or worse. While you're satnding there check your driver's side drive tires. Finding a bolt now is better that wrecking a tire and getting an expensive road call later.
Keep walking. Are your air lines hanging properly. Hangers can break leaving your lines vulnerable. IS the marker light/turn signal operating properly? Check the trailer tires on that side. Last week I found a broken bolt in front of a trailer tire. It was a big one, from a trailer door. No problem, I picked it up and threw it in a dumpster. It could have flattened a tire post inspection. If there is someting stuck in your tire. Do the "water" test to see if it is causing a leak. Get it pulled out as soon as practical. If it isn't leaking, I will pull it out near a tire shop - just in case.
Walk around the back of your wagon. Check your doors. Make sure that they are latched properly. Check to see if your seal is intact. Make sure that all of your lights are working. Look under your trailer and check your mud flaps. A missing or defective mud flap can trigger a full on inspection. At best, those can take up your time. At worst, they can get you put out of service and someone's brother will be called to "fix" it. Someone's brother probably does not work cheap and their work may be dubious. Don't let something preventable attract unwanted attention.
Walk back up the pasenger side of your trailer. Repeat the driver's side quick look. Walk around your cab. Make sure all of those lights are working. Check those mud flaps as well. Make sure your hood is latched on both sides. This quick little inspection can give your peace of mind and save you so much more down the road.