The neuropscy I talked with today told me a typical full evaluation could take 6-8 hours depending on what tests were given and how it went. But since my son was a teen we could probably fit it into two long sessions.

Have you had a conversation about what tests you son is doing? And if he needs all of the tests? This amount of time seems quite long. My DD was tested back when she was 8 and I only remember it taking 2-3 hours in one session.