A large part of therapy is the "tension" one week to the next, the thinking about and working with the material one has generated during the session. If the "steam" is let out in between, then the session doesn't work as well, it's like an old time train. If you want to keep chugging along, getting to where you want to get to, don't waste the energy the two of you are creating in session by dissipating it between sessions.