One of two things generally happens:

1. Coverage runs some/all/none through the “standard” early steps of the coverage ladder, then scheduling skips to QS within 8 hours.

2. Coverage runs through the “standard” steps, but stops before reaching the really desperate stuff (mainly GSWC). With no pilots to take the trip scheduling then starts chopping up the trip and starting over. Then they’ll either reach the point of skipping coverage in bullet 1.

In either case, if they get so close in and have a pilot available for reroute then they will do so. That of course robs Peter to pay Paul, so the newly uncovered legs go through the same process again. Eventually with no takers and no reroutes left they have to cancel flights.