It’s definitely hard to try and cover what can amount to several traumas in ones past along with current traumas. Often a patient may not realize how our past can contribute to our ways of navigating that may contribute to the patients susceptibility to developing ptsd should that person experience something traumatic enough. I know for myself that I had no idea my history made me more susceptible.
Each patient is different and hearing the history can help a trauma specialist map out things that can be important to delve into with a patient that can help them heal and understand better.
Yet you are right in that it can be exhausting to talk about ones history in that a person can be very sensitive to experiencing overwhelming feelings they would just asoon not think about.