The Window of Tolerance is so useful to know; both for the client and for the therapist. It shows the areas where the client may be in their state of being, showing the behaviours they are displaying and matching them within the window of tolerance. The therapist can then adjust the session accordingly and the sessions effectiveness too.
Here is the diagram of the window of tolerance.
credit: nicabm (2017)
Event trauma is treated differently than complex (repeated) trauma, but knowing which state the client is in and having a tool to refer to is invaluable for a client with either. For me as a therapist, to be able to explain and show a client in clear terms about what is happening, can bring a normalisation of the situation. Something for them to go by as well as the therapist, and give them a sense of understanding and that the therapist understands too.