Lanefan
Victoria Rules
Often true, though occasionally a run of bad luck will happen in a situation where fleeing really isn't an option; or one roll will turn things so badly that they're hosed no matter what they do.The dice won't TPK them. Their refusal to change approach or even straight up flee in the face of a run of bad luck is what will kill them.
The latter led to the only TPK I've ever DMed: the "one bad roll" was the party's main Fighter failing a save vs Domination on coming down a ladder into a confined space, and as the rest of the party came down one by one to join him he methodically mowed them down; after which the BBEG (an undead) kept him as a dominated slave until he starved to death.
And as the adventure was set in its own tiny demiplane, there wasn't really anywhere to flee to even had they been able.