Lin Shen's consumption far exceeded that of Ximen Swordsman, but he did not care.
Ximen Swordsman wanted to drain him, and he wanted to drain Ximen Swordsman just as much.
Leveraging strength to transform it into power might be effortless, but it ultimately required some expenditure of strength and stamina.
If Ximen Swordsman were facing someone other than Lin Shen, exchanging a small fraction of his own fighting capacity for an enemy's that was dozens of times greater would indeed ensure a stable victory.
However, Lin Shen was willing to trade dozens of times his own battle damage for Ximen Swordsman's minor losses. Lin Shen could withstand the loss several dozen times over, but it was not certain that Ximen Swordsman could hold out to the end.
Lin Shen's strategy was based on profound foundational strength and great endurance.