Re: do speakers alway shift past simple to past perfect
Yes, exactly, when the direct speech includes the past tense, we may or may not back shift in reported speech.
I am trying to think of when this would not be acceptable, since very little formal writing will include opportunities for "She said that..." type constructions. Perhaps police reports? I'm sure they have their own style.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.