How are some workplace skills learned through doing a job?

Some skills are learned through education, degree, or leadership development programs. However, many skills are learned simply from:

1. doing tasks
2. seeing co-workers make mistakes and get in trouble for it
3. making your own mistakes and getting into trouble for it
4. revising how you do tasks; improving your skill sets
5. taking on more responsibilities
6. making new mistakes
7. showing initiative
8. showing leadership
9. taking extra classes or CEUs
10. using new skills in new tasks