Originally Posted by SlickRick
I work in the IT field, and I would not trust any "timetable." Although the times that each airline is required to submit their updates may be written down, even mandated, they probably don't all adhere to it. What happens if an airline sends the update at 10:00 instead of 8:00? Will the update occur at 10:00 or will it have to wait until the next scheduled update time? Who knows. And how it works today can change tomorrow. It's a good idea, but there is no real way of timing this stuff. Just the way the world works.
I work in IT as well, and I can tell you what
Vulcan said is correct. The systems update at specific times during the day. I don't remember the times off-hand, and sure there's often a negligible variance by a few minutes here or there, but there are definitely set times for this to happen.
And to answer your question, if an airline submits an update after the window, it will indeed wait until the next window. The one exception being the airline's own computer system -- they have full control over that. So, if a carrier pulls a fare, it's not uncommon to see third-party sites have access to it, while the airline itself does not.
Since we're on the CO board, it's probably worth noting that CO is usually pretty good about adhering to standardized release times for its own updates. I've seen fares come and go, and CO is usually in line with those release times (within a few minutes). As they should, otherwise CO is exposed with their lowest fare guarantee.
UA, OTOH, has a nasty habit of pulling fares at will, so you're often forced to go through a third party site if you're trying to catch a fare that's on its way out.