When DS tested with the WISC IV he was 9years 10 months or so and I think it was well over 2 hours as well, and the SB5 a year latere was at least 3 hours. They had scheduled the morning for the SB and the WJ, but he didn't get done with the SB5 until almost 1:00. He was pretty hungry and tired and we postponed the WJ for another day.
He had enough ceiling scores on both tests that everyone thought that the scores were an underestimate and based on his recent ACT they probably were.
When people recommend testing by 9 for HG kids, I think they mean by the time you turn 9 (if your goal is to see how high the score is. If you're looking for LD's then I think it's different), because for us 9 going on 10 was probably too late to get the most accurate score.
