Few, if any, CDL students feel they have had enough training by the time school ends. The point of school is to pass the CDL test and get your license. The place where you learn and practice the skills will be with the trainer at your first company.
After you learn & practice backing, navigation, customer procedures, weighing & sliding tandems, etc. Then toward end of your training period when you are doing everything while your trainer is asleep is when you first feel like you have enough training.