Not only is Samuels stuck in the 70's, he is pushing 70. His CV shows he got his undergrad degree in 1965, which would make him 68-69years old. It also does not list any continuing education within the past ten years.
In his 35 years, he has administered this PSD test 15 times, so it would appear that he does not have extensive experience in this area.
IIRC, at least three times in his testimony he made comments about discontinuing certain areas of practice because they were not lucrative. Most people who have been successful in their careers would be retired by this point in life; I don't sense any dedication on his part and believe he is still working because he cannot afford to retire.
In terms of experience, I'll take quality over quantity.