My T describes it, at least as related to memories and experiences that are "stuck" for us (keep coming up again and again, we can't get past them), as there being two containers in the brain. Memories go into one container and then get processed and pass to the other (longer term storage, perhaps). Some memories get stuck in the first container and never get out--they remain in a more accessible part of our brain and keep coming up. So a therapist helps the client process those and get them to move on to the other container. If what the therapist is doing is not helping the client process the memories, then the T should try a different approach. Trying the same thing 8 times with little success is not very encouraging for the client, and is painful. That is one reason my T really likes the faster therapies for the very stuck memories, such as EMDR. Maybe it's a bit like bringing in the bigger guns for the really recalcitrant problems. He thinks EMDR (and some of the other faster techniques) helps things pass between containers more quickly. I have had some good success with EMDR, but also feel that regular talk therapy can help me with these things too. I guess part of what technique we use depends on my energy level, how awful the thing is, and my degree of feeling, "I just want to be done with this--HELP!"