I will continue under the assumption that you want to tap into the creative possibilities of our species rather than treat people like unfeeling machines.
Organizations share the responsibility to make sure every employee is being developed professionally every year. Every personal performance goal statement should include a professional development objective.
It is the uninterrupted walk of 1,000 days that brings real, sustainable growth; the accretion of tiny layers of knowledge and experience that build a strong mountain that will not erode.