If your strength is inferior, then the best way to attack is by surprise.
However, Ye Wan said that it's not always possible to keep oneself in a dominant position, and while surprise attacks are important, solely pursuing how to launch them would only be considered opportunistic trickery.
Qing Chen kept trying attack movements relentlessly, showing no signs of fatigue.
In his hand, he held a genuine Spring Knife, and his opponent was not the air, but the flesh-and-blood Ye Wan.
Ye Wan was like a mountain, no matter how fierce Qing Chen's attacks were, he was able to block them with ease.
If the first step was to identify the vital points,
then now it was the second step: Routines.
Logically, there aren't many angles for striking the spleen, just a few.
But what Ye Wan taught him was how to feign one's intent, making the opponent misjudge the intended target, and then open the path to the spleen for you.