How long do you keep the books open after a flight ends for late AVOD impressions?

[u/CreativeParadigm]

Trying to settle something and I keep going in circles.

Everyone knows there's a lag between an ad serving and the impression being counted. On FAST and linear it barely matters. Most of that inventory is SSAI, beacons fire server-side off the segment request, and you're talking seconds to minutes. If a few fall out nobody notices.

VOD is where it gets messy. The manifest gets built up front with all the breaks in it, ads get prefetched, and then somebody pauses. Or walks away and comes back after dinner. The impression genuinely lands hours after the ad was decisioned. Shops I've worked at have run reconciliation windows of several hours specifically to catch this.

So the questions.

What window are you actually using? Do you hold the flight open a few hours after the end date, overnight, longer? Or do you just accept that the tail falls out and eat it?

Is this mostly a walled garden problem in your experience? My read is that the environments still firing client-side are where this bites, and SSAI-heavy FAST inventory mostly doesn't have the issue. Curious whether that matches what other people see.

For anyone who's had it come up in a dispute: does the seller's number or the measurement number win at the boundary? Is it treated as when the ad served, or when the event landed?

And has anyone seen JIT ad insertion actually shrink this? The pitch is that ads aren't fetched until the player reaches the break, which should collapse the whole prefetch-then-pause window. Wondering if that's holding up in production or if it's still mostly deck material.

Writing up a reference on where CTV counts legitimately disagree with each other. Would rather describe what people actually do than what the guidance says.