Often the most useful thing a clinician does is not delivered by the clinician. It is delivered by the teacher, or the parent, after a conversation you had with them.

What the research says

The foundational review of psychosocial treatment for ADHD established behavioural parent training and behavioural classroom management as the well-supported approaches, and both of those are delivered by adults in the child's daily world rather than by a clinician with the child. Where the evidence sits says something about where the effort should sit. It is a review of the child literature and does not settle how adult work should be arranged.

Strength of evidence: one line of research. A single study, or a theoretical account.