Teaching is a skill. Aspects of teaching are charismatic and intuitive; however, charisma and intuition alone do not make a good teacher. Obviously competency in the subject is a prerequisite to teaching but competency-- even excellence-- in a subject does not make someone a good teacher.
I believe teachers should ask for peer evaluations with some regularity, maybe once every year or two. Find someone who teaches groups of people and ask them to watch you teach and give you feed back and suggestions. The evaluator could be someone who teaches martial arts/qigong but that isn't necessary. Good teaching is good teaching. Mediocre teaching skills can be improved once the deficiencies are understood.
Asking someone in your lineage to evaluate your teaching may be a good idea but it is a different process. The simple fact that they teach the same or similar material is likely to get in the way of good feed back.
I get evaluated as a teacher twice a year by peers at Performing Arts Workshop, and the criticism is always helpful. I also attend regular teaching skills workshops. I've been evaluated three times by peers at the American College of Traditional Chinese Medicine.
I learned a trick at my last evaluation that other teachers might find interesting. It's called "One Minute Papers." Hand out pens and half-sheets of scratch paper to your students and ask them to write to you for one minute-- questions, feed-back, thoughts, whatever. Do this at the beginning, the end, or during a break in your teaching--let them beanonymous if they want to. By doing this I learned that students often have questions they don't feel comfortable asking out loud. I also learned that students can polarize to extremes--like for instance, half the class wants me to stop and explain, while the other half wants silent practice time.
Getting eyes and ears on the outside can make even a great teacher better.