My daughter has a BM and MM in music. She did trial lessons whenever she could. The teachers are interested in how you are to work with–in your potential as much as in your preparation and so-called talent. A trial lesson, or “playing for a teacher” (in the case where you get a brief audience but maybe not a full lesson are important, if you can get them, because it allows the student to have a glimpse of the teacher’s style and approach. It’s all about fit. Some trial lessons my daughter took were after acceptance (some teachers can’t or won’t schedule until after they know who has been accepted.) They were absolutely essential in picking where she studied.