The Importance of Maps......

Some routes you can't take with a truck as Wall Eye stated above. Folding maps are good to find places that you may not find on your atlas. I had a Motor Carriers road, atlas but a very cheap one, and Otay Mesa California wasn't on it, and I needed to know how to get around there. I was with my trainer at the time, and he had the deluxe one, which is the extremely pricey one. It was on that one.
I figured it this way. Roads change year by year, so even if you buy the deluxe Motor Carriers Rd atlas, it may not be fiscally responsible to do so every year. If you can afford it more power to you. But with a good combo of the Motor Carriers road atlas and other maps, then you should be able to easily plan your route.
I always carried a small inexpensive pocket sized, road atlas, the kind you can pick up at the check out line in walmart. I put that, with my pocket sized truck stop guide, and if I needed to pull over at a truck stop, all I had to do was find look at both, and get a good general feel of where I needed to go without lugging out the heavy artillery of better maps. You can't plan a route with such a map, but it feels good to be able to consort it for basics such as exits etc.
The more maps in your arsenal the better off you are, or atleast that's what I found.