The WPPSI4 has different subtests to the v3 (it does have some overlap but some are completely new or are similar to the WISC). When my DD did the WPPSI3 she had two 1.5 hr appointments, it wasn't fast, it was excruciatingly slow, AND often by the time she'd gotten to her level she was completely tuned out and more focused out the window than on the test, especially the cartoon based tests, which she did not care for at all. She found the SB5, with the routing questions, much easier going as it was done and dusted in 1hr.