Schact truly was brilliant. Speer was of average intelligence among the men in the docket according to the IQ scores which I have seen as well.
What saved Speer from the gallows was his truly heartfelt contrition—a trait noticeably absent from most of the other defendants who tried to avoid responsibility by simply saying they were following orders.
That Schacht, who spent much of WWII plotting against Hitler and sitting in concentration camps, was charged with war crimes was simply ridiculous. I regard him, along with Col. von Stauffenberg and FM Rommel as a true German heroes and patriots.
If you want to have some real fun, watch the World at War series. Speer is interviewed extensively in it and he is clearly caught in more than one lie.