The on-site interview is essentially an all-day SAT. You will spend very little time talking to a person about your qualifications, and a lot of time taking standardized tests. There isn't really any way to prepare for this, except for practicing SAT/GRE kinds of questions. This might be a good way to weed people out for programming positions, but it is well established in the education community that standardized testing is a poor reflection of ability, especially for something like Corporate Trainer, where the essential skill is communicating with people. They like to advertise that they have a very "smart" staff, but hey, I'm a grad student at UW Madison (and a teacher), and I didn't get past the testing. So how did I get into grad school? Well, thankfully schools look at the whole person, not just a bunch of test scores. Epic passes by a lot of qualified people in the interest of streamlining their interview process. Their loss! Don't waste your time unless you happen to be a good test-taker.