It is VERY important.
I agree with danny: figuring out what works with each individual student contributes to the teachers' development; however, there is much more to it.
- attend conferences, workshops, meetings (this is an invaluable contribution to you as a teacher as you meet other teachers, talk about issues, collaborate on new ideas, hear from experienced pedagogues, etc.)
- become certified through MTNA or whatever your national organization
- become certified in other teaching methods/approaches, such as Suzuki, Dalcroze, Musikgarten, etc. . . This doesn't mean that you will ONLY teach this way, but it will definitely give you different perspectives and tools that you can use in your teaching
- have your students participate in evaluations, examinations
- find out how to get involved in being a judge, adjudicator at local events (or on a bigger scale, become a member of the College of Examiners for the Royal Conservatory of Music, Toronto)
- visit other teachers' studios, observe lessons, interview them, etc.
- give recitals (solo, or collaborative with other teachers: duets, duos, chamber music, etc.)
- even informal meetings with other teachers can be helpful. Our local branch of the national organization (MTNA) holds meetings at various members' homes. We play pieces for each other (motivates us to practice and keep playing/learning), we sight-read duets and duos together, get others' opinions on interpretation of pieces, etc.
There is MUCH more, these are just a few ideas. I'm no expert, not a seasoned veteran here, I'm sure other people can give other ideas . . .