I would politely inquire as to what kind of questions testing was raising. I do find that sometimes one result leads to another test, but always with a hypothesis of some sort, not just a fishing expedition. It sounds like she was anticipating about six or seven hours of straight testing (based on four two-hour sessions, plus some rapport and interview time). A cognitive would take up one to two hours. Achievement could be anywhere from one to four hours, depending on the instrument and the depth. Memory usually takes about an hour. EF tests vary, but could be a few minutes to an hour plus.
The length of the testing does not surprise me per se, but the fact that an evaluator experienced with gifted young children can't predict how long it will take is clinically significant. My guess would be that she is chasing down a suspected 2e or severe case of perfectionism (which might be considered a variant of anxiety, which I would also consider 2e).
