I've done some intensive psychoanalytic work that almost require "regression" though the idea is that you can have the strength to "come out" of that and continue your life. I have had periods of pre-verbal regression that were very intense. They didn't happen in session, but when I tried to call my therapist to reach out, it was really difficult at first because I was barely able to be verbal. Luckily he has lots of experience so was able to calm me down enough to re-establish a connection to a way to verbalize my experience.

My current therapist doesn't believe in "re-parenting" per se, but he does believe that fundamental "reparations" happen in the intimacy of the therapeutic relationship that relate to early developmental failures. It is a bit more broadly conceived than the idea that there is an inner child. It more like a structure that has some weak points, even though the actual experiences are more like feeling "little" or "young" and then when asked where I am or what age I feel, I'm actually able to get out of dissociation into a partial foothold into the here and now. It really depends on so many factors, your history, your therapist and their approach, what your life is like, what current relationships you have, all sorts of things, too many to list.