Close relative of mine worked as a seasonal reader for one of the HYP’s for several years.
Folks- the purpose of the training (whether 3 days, 5 days or 7 days) is NOT to turn the Readers into Adcom’s, where a significant amount of training, judgement, experience, etc. is required. The purpose of the training is to get the readers to the point where they can take a stack of 100 applications, knock out the “Hail Mary Pass” kids (B students with 1150 SAT’s who write in their essay “I’m applying because Grandpa says that his four years a X were the highlight of his life”, knock out the kids who are ranked 70 in a class of 300, no extra-curriculars, average recommendations, at a well regarded HS in an affluent area where the college WILL take 4-5 kids every year-- but not this kid, etc.
That gets the stack of 100 applications down to a more manageable level, which the Reader then is able to score using the ratings system (which the Reader applies, does not create) to assemble an even MORE manageable pile which then goes to the Adcom for that region for the hard stuff.
My relative was an active alum of the college, advanced degrees, professional experience in education, etc. As were the fellow “Readers”. It’s not like Princeton is taking clerks from Wa-Wa and trying to teach them how to score an application.