My T once told me that a therapist must be able to compartmentalize. He must keep his own problems out of the sessions. He must keep his sessions/clients separate from each other in his mind, and he must keep his work/clients out of his personal life. Failure to be able to compartmentalize, he went on, is the leading cause of burn-out for therapists.

There is a reason beyond our own welfare for those boundaries so many detest. Those boundaries serve as self-care for our therapists.

That doesn't mean they don't answer an emergency phone call, etc., but they have to draw a line in their mind in order manage the information and emotional overload that could certainly overwhelm them if not kept in check.