I got my driver's license in one go with Ralf. The thing with Ralf is that you should do your part for him to help you. For me it was easy to learn, as I already knew how to drive, but Ralf gave me insights and tips on how to drive here in the Netherlands, especially with priority, and he trains you in the standard that the CBR wants you to be. It was very helpful; in the last week before the exam, he gives you extra lessons, which really come in handy in my practical exam.