As a hypothetical, let's say my offensive playbook has nothing but passes where WR1 runs a hook every time. Is the defense smart enough to recognise that this is happening? Yes, there's a play overuse penalty, but does something similar happen for pattern overuse?

No, not in the current engine version. It's something I'd like to add, but obviously that gets much more complicated in the AI to write, so it's not been a high priority against the other todo items.