License mills don't help you develop the complete range of skills and knowledge necessary for workplace success. But how do you tell if a school's focus is upon test success at the expense of workplace success? In other words, how do you tell if a school is a license mill?
Sometimes the school itself will tell you without meaning to. If a school says its off-road instruction consists of "straight line backing, alley docking, and parallel parking" you can be sure you've found a license mill. These maneuvers are the maneuvers found on most CDL skill tests, but simply learning to pass the license test fails to prepare you for the real world.
You should also be suspicious when a school offers only vague descriptions of its course. For example, some schools will claim to provide 200 hours of instruction (or even more) but will not distinguish between actual instruction and observation time. It's possible for a school to claim huge hours of instruction if the standing around time is included in the total.
For this reason you should insist that the school tell you exactly how many hours of actual, behind-the-wheel (BTW) time you'll receive. Remember that standing in line with your classmates as you wait to practice with the truck doesn't prepare you for your new career.
You should consider the style of the school's operations. Are the classes large? Does the school operate like a factory designed to crank out drivers? Some schools boast about how many graduates they can "pump through." As you prepare for your new career do you really want to be simply "pumped through?" Or are you looking for something more?
When comparing schools you should ask if the classroom instructors are available for additional tutoring if necessary? Do the classroom sessions resemble real learning experiences? Or do the classes remind you of high school driver ed. with lots of stupid movies and meaningless busy work?
Is the overall experience impersonal and hurried? Do the people making the promises seem entirely trustworthy? Do they really understand trucking because they've worked in the industry for many years, or are they just fast-talking salesmen? These are the sort of questions you should consider as you decide how best to prepare for your new career.