For COVID-19 rescheduling that happens before teams have exhausted their bye weeks, the league has a computer model that spits out potential solutions. (Today’s solution for the rescheduled Broncos-Patriots was far from simple.) As teams have their bye weeks, it will stop being easy.
The league acknowledges than an eighteenth week of the regular season is “in play,” but the league wants it to be a last resort. Before using an extra week, the league will strive for maximum flexibility and adaptability, with the goal being safely and responsibly playing all 256 games within the 17-week schedule.
Parking games in an eighteenth week now would limit options if/when issues arise later in the year. As one source with knowledge of the dynamics explained it to PFT, there’s a concern that teams would become complacent if they believe they have a buffer.
There’s another potential problem: If/when even one team needs to reschedule two games, an eighteenth week won’t be good enough. Which would put a nineteenth week in play, in order to get all games in.
So the eighteenth week truly is an emergency option. Soon, however, it may be time to declare an emergency.