Some teachers are very useful, some a little bit useful. Some can be a bit harmful as well. It is the student's responsibility to understand what a teacher has to offer and to relate to that in as positive a way as possible. To help in this difficult responsibility, it is useful to know that what a teacher is offering can be seen to be in one of three categories. Using the image of a tree, teaching can be like the roots, like the trunk, or like the fruit. If you understand what level is being offered to you, you will be able to gain benefit from nearly all encounters with teachers, as well as with colleagues.
Teachers at the level of 'fruit' are the ones who offer no details but expect finished perfection from their students. When something needs correction, they simply say, "make it sound like this." They are asking you to be a finished musician from the start. Many jazz musicians teach like this, as did Julius Baker, which is great, but if you are like most of us and need a little problem solving from time to time, this can leave you with problems unsolved.
Teachers who teach in the style of the tree trunk are the ones who help you with professional training. Of course this is very important, but if the teacher focuses too much on audition repertoire and working skills, this kind of teaching lacks artistic vision and historical fundamentals, because those are beyond the scope of practical training for imminent auditions, recitals or professional work.
Teachers who are 'roots' teachers are the ones who can help you build your fundamental skills, skills that are not just for beginners, but, like roots, grow deeper as the tree grows taller. A teacher who can provide classic step by step instruction in how playing your instrument really works is a great treasure. Roots level work needs to include very concentrated listening to living and past masters and a growing understanding of stylistic traditions and ways of playing.
With this in mind, as a student you will be able to discern what type of benefit each teacher can be for you. Ideally, there should be some of all three levels in each lesson, but it is the rarest teacher who has all three levels working completely. Understanding this can be of great benefit.