I think the biggest contender supporting professional development, besides the obvious factor of continuously evolving and adapting with time and for the benefit of students, is dedicated time where teachers learn from and collaborate with other teachers. No matter your years accumulated as teacher you can bring something to the table or learn something from another teacher. Just like all our students are different and function best in different ways, teachers teach and function best in diverse manners which makes collaboration all the better. Another teacher may suggest or share a teaching technique you may have never thought of. This all varies from work-life balance, classroom management, relationship building activities, classroom norms, and so much more.
My very first day of student teaching was a professional development day at the start of the school year for teachers to meet new teachers, share their stories, learn about whole school expectations, and other teacher duties outside of teaching in their classroom. All very beneficial things to know in order to be a strong team of teacher and admin, as well as the best teachers we can be, in the school we are at, for our students.
One of the first thing we talked about was why we teach, the principle broke us into groups of roughly 5-6 teachers and we all shared. Getting this opportunity to hear other teachers' stories was very enlightening and unlocked the words I needed to share/identify mine. This will be a great thing for me to be able to identify because it is your selling point in interviews but also a great reminder for yourself when teaching can get difficult.
A lot of the professional development that I participated in were meetings that happened during lunch or after school, and we talked about things like relationship building, test score percentages, behaviors, and building relationships, all things that are very integral in understanding and evolving with as a teacher.