I have been a student with Katrin for over two years now. She takes a lot of time, but doesn't give up on unlocking your full potential. During the hour, you may well curse them quietly. After two days at the latest, you will be grateful for their persistence.
It's easy to walk past the studio because it's located in the inner courtyard. Simply enter the first courtyard entrance to the left of Schmitz Katze, then the staircase is at the back on the right. The studio is on the second floor.