Last week I reread Mamet's short book of essays, Theatre.
At one point he was saying that the whole point of a story, in theater, is to keep the audience guessing what will happen next - that is, keep them interested - that is, keep them following the plot.
And it occurred to me that if you start with "Keep Them Wondering What Next" as an axiom, then having a logical but surprising story is best because they feel they can sort of see ahead but not quite. So they lean forward in their seats.
You promise they'll be given a fair shot
and they feel cheated if they're not.