When you take the sunroof cassette down, you will see how much space there actually is for debris to collect. It will be fine for a while and all it will take is one good rain and all that debris will collect around the drain making water egress a lot slower. Then it will overflow and drip inside.That's why it explains why water was not going through the sunroof for 2 weeks and it started to leak again because the hoses are kinking?