Being a leader is demanding, and finding the time to reflect and develop oneself can be challenging. If the accountability and transparency of such reflection is non-existent, the probability of it happening diminshes even further.
To help leaders build awareness of the skills, behaviours and priorities required of them (and how well they master those expectations) you should provide leaders with tools for reflection, reflection logging and reflection transparency.
This might include surveys, assessments, role descriptions, skillset descritions and other relevant resources where the leader can evaluate and write down their thoughts on their own ability to adhere to best practices.
For a collection of such resources, check out the leadership support category.