I think that often in therapy we are encouraged to increasingly let down our barriers and defenses. During and after therapy our emotions are a bit raw sometimes and we are (I am) contemplative. I think that somehow we continue to need our safety or think we need our defenses so up they go up again between visits. In time the defenses for certain issues become less needed as we work things through... Then on to the next thing... all over again...somewhat. It can vary with the issue and with the level of trust we may have with our therapist....(or even with ourselves.)