It's not just a FAYZ discussion

By the end of the book, we should know what the countdown clock was counting toward. But I'm still a bit unclear...

Was it counting down to
(view spoiler)[the collapsing of the tunnel?
the death of Drake?
the death of the Gaiaphage?
the death of Duck?
(hide spoiler)]

Am I missing something obvious? To me it seemed like there was more than enough tension without the clock. None of these events seemed to have been resolved fully enough/were significant enough to warrant a countdown clock.

Lies starts another countdown clock!

I love the countdown clock because it is original and I love how the whole book takes place in 5 days. It is simply counting down to 'the climax' of the book.

I thought it was a countdown to Sam's birthday.

oh wait JK that was the first book. Haha my bad.

Yeah. I think it was the climax. But it is unclear. Not like Gone and Lies.