Between-session support
Between-session support is the help and structure a person has in the days and weeks between appointments.
Between-session support covers everything that holds the work up when nobody is in the room: what you do on your own, who you can reach, and whatever structure you agreed to before you left.
It matters because the time between appointments is most of the treatment by volume. An hour a week is a small fraction of a life, and the rest of that life is where a new pattern either takes or does not.
In practice it takes ordinary forms. A written plan for a hard day. A person you have already agreed to call. Small tasks agreed with a clinician. A record of what you noticed, so the next session starts from something specific instead of from memory.
The distinguishing feature of good between-session support is that it was arranged in advance. Support you have to invent while struggling is much harder to reach for than support you set up while steady.