LAF, 3.5 hours is a pretty typical time for a comprehensive cognitive and achievement battery. In my typical eval, I take about 15-30 minutes on a preliminary interview of the student, and rapport building exercises, some of which double as social-emotional screeners. The core battery for the WISC-V takes about 45-60 minutes, but can easily take half an hour longer, depending on which ancillary/supplementary subtests are added, and can take even longer than that if I have an unusually slow-moving student (for whatever reason, including having an early start point, but late discontinuation, such as may happen with a young GT student). A comprehensive achievement like the WIAT-III or KTEA-3 takes about 1.5 hours to 2 hours to complete, again depending on added subtests and work pace. The WJ-IV can take even longer than that, if all additional subtests are administered, especially now that they've split the old cognitive and achievement batteries into cognitive, achievement, and oral language batteries.
You should have some idea of what they were doing, based on the consent to test that you signed prior to the assessment. Though some districts do send blanket consents. Did they list assessments or assessment instruments on your consent form?
