70-20-10

The 70-20-10 Model for Learning and Development is a learning and development model that corresponds to a proportional breakdown of how people learn effectively; based on a survey asking nearly 200 executives to self-report how they believed they learned.
In this survey respondents reported the following learning tendencies:
● 70% from challenging assignments
● 20% from developmental relationships
● 10% from coursework and training

Source: https://en.wikipedia.org