Interview prepping and ATP written studying in advanced.

I have to go through the ATP-CTP and I know that he ATP-CTP really isn't going to help me out much on the written (or so I've heard). That being said studying in advanced on the interview will help freshen me up on that knowledge. Shep offers some interview prep with the ATP specific for regionals-

I'm gonna go ahead and buy the ATP prep, should I spend the extra bucks and do the interview prep as well or just stick with one? I have all the gouge off AirlineInterviews.com and have been studying that, just didn't know if this would be a good addition?


Anyone have any advice or experience one way or the other?