The considerations for mentoring programs in organizations are many. It needs to be distinguished from coaching. It works better when people choose their own mentors from crowdsourced reviews on mentor strengths. The idea of multiple mentors simultaneously and across career phases and careers is smart.
Many people who could mentor do well developing the art of it from seasoned mentors. Being a leader, expert or veteran does not automatically qualify someone as a good mentor. Mentor communities of practice help with this development, as well as coaching with experienced and expert mentors.