The veterans who have fought in wars know that defeat isn't a slow process, it's something that happens abruptly.
Victory is not about annihilating the enemy completely, in fact, it's about disrupting the enemy's organization, then the defeat naturally ensues.
This is the meaning behind the saying "defeat is like a landslide".
Experienced generals understand that once the frontline troops collapse, sending reinforcement troops might seem like the right idea, but, in actuality, it is the most foolish decision.
Because the collapsing front-line forces would break up the organization of the reinforcing troops, leading to a defeat as swift and massive as an avalanche.
This is why feigned retreats to lure the enemy is rarely seen in real-life tactics.
Unless one has absolute confidence in their command skills and their warriors' loyalty, most leaders wouldn't dare to use this strategy, as one misstep could turn a feigned defeat into a real prostration.