With respect to Why didn't they use the yoke trim switches effectively?
How much or how little, rather, hand flying experience did they have?
Captain was cadet from the start at ET, operated from the get go in an "AP on at 200' and off at 1000'/500' " SOP environment, and the FO was brand new in just such an environment. Unfamiliar with using trim switches whilst flying .. unfamiliar with hand flying, and having to do it with the stick shaker on max continuous with unreliable airspeeds. Ouch