Not that predictable at all it would seem. A heavy reliance is based on the explosion of current affairs - and they can not be tamed.
The New Yorker put its site behind a metered paywall in November 2014. The expectation was that traffic would go down, and not much thought was given to subscription results. As it would happen, traffic went up by 30 percent within a few months and subscriptions grew 85 percent year on year.