It's all very well saying we should know the FCOM inside out ( true) but it's one thing being able to recite the books, it's another one understanding every subtle nuiance and logic trap that the designers may have buried in the system- and there are more than a few. Over the years on a couple of the big Boeings I've certainly seen manuals and company training " morph" as yet another aspect of the autothrottle system has been discovered by some poor so and so on the line....(and I'll fess up and say been there and explored the system logic, or apparent lack of it on a GA from a lowish platform altitude one dark and not so stormy night....)
However ultimately yes, you have to be prepared to get rid of the automatics.