Merlin,

I am no expert in the WISC testing, I am just speaking from my experience with my DS8's testing. He was close to 7 years old when he took the test. It took him almost an hour and a half to complete the test, without a break. He only took the first 5 subtests. The tester offered a break between the 3rd and 4th, but he declined so they kept going. Also the more right answers you give, the more questions you'll get and the test will last longer.