We did a psychoeducational profile on our son and their estimate of time was way off as well (possibly the same well regarded office). They had said one 3-4 hour session and it ended up being two 4 hour sessions. That was double the time they expected. A highly gifted kid could easily use up way more time than expected just on the IQ and achievement tests.
Perhaps you could ask to do longer sessions to finish faster? Two hours seems to be a rather short session. I think it's important to get a list of what tests have been completed and definitely ask about the 2e scenario. A learning disability is common with highly gifted kids.
