I noticed from playing that the hostage count ticks down really quickly on a first pass and yet we've been waiting at the helipad at the end of levels. Checking this out, it turns out as soon as you despawn the hostages on screen, they'll count immediately and you can advance slightly faster.

With that in mind, I think it makes sense to change the run end point. I'd suggest the frame hostage remaining count reaches 0 as an unambiguous point. Thoughts welcome!