Implementations relate to generating a proficiency measure, and utilizing the proficiency measure to adapt one or more automated assistant functionalities. The generated proficiency measure is for a particular class of automated assistant actions, and is specific to an assistant device and/or is specific to a particular user. A generated proficiency measure for a class can reflect a degree of proficiency, of a user and/or of an assistant device, for that class. Various automated assistant functionalities can be adapted, for a particular class, responsive to determining the proficiency measure satisfies a threshold, or fails to satisfy the threshold (or an alternate threshold). The adaptation(s) can make automated assistant processing more efficient and/or improve (e.g., shorten the duration of) user-assistant interaction(s).