hello, there is no tailor made answer for this since it asks regarding personal experience. I assume you posted this question here not able to figure how to relate your experience to the model.
ATD competency model emphasizes foundational competencies and Area of Expertise.
Foundational competencies relate to the basic knowledge possessed all the individuals belonging to the specific field.
Here, the question focuses on Area of expertise. So, we shall discuss about it.
I worked in a startup as well as a MNC. That helped me figuring out the differences and the gap existing.
While working in the startup, we were a small team. When it started to grow, we figured out on dividing tasks, reporting and culture to be set for new comers. So, I can say that this helped in gaining expertise related to change management.
Similarly, we set a feedback session after every event to discuss what was done, list of things, mistakes made, what to be done to overcome it. Maintaing a database in this helped us to improve by making sure same mistakes does not repeat. This can be seen under Knowledge Management.
So, my experience helped me in practically implementing these and gaining expertise. This expertise helps in my career in T&D in the fields of change management and knowledge management.