For those who obtained their military driving licence from NS, need to accumulate a certain milestone mileage in order to be eligible to convert their military licence to the civilian Class 3 licence. In most cases only those driver who get to drive almost daily would be able to qualify, such as those MT Line drivers etc.
If one's main vocation is trooper but taking extra driving lessons to drive a landrover driver who only gets to drive during the occasional unit exercise, can never qualify due to the lack of mileage.