If rigor mortis is temporary in zombies, then escape strategies must be adjusted to account for the window of “dead” time at the height of rigor.
The theory is that a great wave of panic and violence will sweep infected areas over the first several hours and days of an undead outbreak. Many will try to flee, so the roads will be clogged and dangerous. Complete chaos will ensue as the rule of law breaks down, and the number of zombies roaming the streets increases rapidly. But a lull is coming.
As the outbreak progresses, many zombies will begin experiencing advanced rigor mortis. They’ll be stiffening to the height of rigor, or loosening up after the height. Either way, they will be moving very slowly, if at all. Therefore, this could be the best time to make for the safety of a remote, unpopulated location.
The problem is, if you go too early you’ll be met by scores of gnashing, fast zombies, and terrified, irrational humans. By contrast, if you go too late the zombies will be up and running again in even greater numbers. So pick your window wisely.