It's just not always clear there's even an option IMO. I ran The Goblinblood dead today and the
Now, we can argue that a careful DM would have made note of all that and broached it in the conversation somewhere but it could be a really easy thing to miss. Without the deliberate emphasis as given in the faction mission, it's hard to blame them for not discovering there even was an extra mile to go. And the worst part is it's actually specific to those devices. If the PCs had decided to dig a moat for them it wouldn't have counted scenario as written.
It's just not my cup of tea as it stands. I'd be happier if the secondary missions were handed out like a group faction mission of some sort and not this fumble and hope you find.