As far as I am concerned, a supervision process is not a technical process at all. It is an encounter that can be meaningful and emotional. In the supervision process, one touches theoretical materials, therapeutic techniques, knowledge, alongside meaningfully dealing with issues of transference, countertransference, therapists' blocks, beliefs, and outlooks on life and their impact on the therapeutic process.
To me, supervision is a field sometimes enabling the incorporation of delving into personal issues, therapeutic "dives", if you will, into the supervisee's world, in order to help them be a better person and therapist.

In terms of my personal experience, over the years I have provided individual supervision to specialist clinical and educational psychologists, and ones who were in the course of their internship and preparing for their certification exam.
I have supervised psychotherapists during their training at the school of psychotherapy, as well as veteran psychotherapists from various therapeutic modalities.
I have supervised practicum groups and multidisciplinary teams of psychotherapists and psychologists.
Nowadays I mainly supervise individually, as well as teach continuing education programs and provide prolonged, ongoing supervision to psychological service teams, mental health stations and settings.