Training and teaching is hard. "One hour of interviewing could be avoided with one hour of training" is wildly optimistic.
It also ignores the breadth of knowledge you likely want a candidate to have (and are just trying to sample at through a short few interviews). How many hours of training are you willing to sign up for? How confident are you that the knowledge will "stick" for any given candidate? Are you going to fall back to GPA and school prestige to measure how well they've retained knowledge in the past? That seems like a step in the wrong direction.
I don't think it's wildly optimistic, but perhaps we are thinking about it in different ways. I don't think I could teach someone how to implement each data structure in an hour, but I could easily go over maps/queues/stacks/hashtables and tell you when to use each in an hour. I know this because I do that very thing in less than an hour in code reviews.
I do agree that the "stickiness" is iffy, but it usually sticks pretty well. You then have a second problem that can be described as "when you have a hammer, everything is a nail" as they use their new fancy hashtable everywhere.
It also ignores the breadth of knowledge you likely want a candidate to have (and are just trying to sample at through a short few interviews). How many hours of training are you willing to sign up for? How confident are you that the knowledge will "stick" for any given candidate? Are you going to fall back to GPA and school prestige to measure how well they've retained knowledge in the past? That seems like a step in the wrong direction.